How to Cook Costco Top Sirloin

Costco top sirloin is a boneless beef steak from the Kirkland Signature line. It comes in both USDA Choice and USDA Prime grades.

The meat department packages these steaks in multi-packs weighing around 3 to 5 pounds total.

Most home cooks grab this cut for weeknight steak dinners or weekend grilling. It delivers solid beef flavor without the ribeye price tag.

This guide covers four cooking methods. Total cook times range from 10 to 25 minutes depending on your approach and preferred doneness.

You will need a meat thermometer, cast iron skillet or grill, and basic seasonings.

Product Details

Product: Kirkland Signature USDA Choice/Prime Beef Loin Top Sirloin Steak Boneless Cap Off

Type: Fresh, raw beef (refrigerated, not frozen)

Package Size: 3-5 lbs per pack (4-6 steaks)

Price: $8.19-$9.99/lb for Choice, $10.99-$11.99/lb for Prime at Costco (Updated January 2025)

Storage: Refrigerate at 40 degrees F or below. Use within 3-5 days of purchase.

Calories per Serving: 180 calories per 3 oz cooked serving

Main Ingredients: Beef top sirloin

Nutrition (3 oz cooked): 26g protein, 8g fat, 0g carbs

Cooking Methods Comparison

Recommended Method: Cast iron pan searing produces the deepest crust and most consistent results for top sirloin steaks between 1 and 1.5 inches thick.

Method 1: Cast Iron Skillet (Recommended)

Pan searing takes 8-12 minutes total. You will get a deep brown crust with a juicy pink center at medium rare.

This method works for 1-2 steaks at a time. Finishing in the oven handles thicker cuts without burning the outside.

Step 1: How Do You Prepare the Sirloin Steak?

Remove the steak from refrigeration 30-40 minutes before cooking. Room temperature meat cooks more evenly.

Instructions:

1. Pat the steak completely dry with paper towels on both sides
2. Season generously with kosher salt and black pepper

Equipment: Paper towels, cutting board, salt, pepper

Step 2: What Temperature and Time Do You Use?

High heat creates the Maillard reaction. That is what gives you the brown, flavorful crust.

Instructions:

1. Preheat cast iron skillet over medium-high heat for 3-5 minutes until smoking
2. Add 1 tablespoon high smoke point oil (avocado or vegetable)
3. Sear steak for 3-4 minutes per side for a 1-inch thick cut

Temperature: Medium-high heat (skillet should be smoking)

Time: 6-8 minutes total for medium rare on a 1-inch steak

Step 3: When Do You Flip the Steak?

Flip once after 3-4 minutes. Do not move the steak around before that.

Instructions:

1. Check the bottom at 3 minutes for deep brown color
2. Flip when the crust releases easily from the pan
3. Add 2 tablespoons butter, crushed garlic, and fresh thyme during the last 2 minutes

Checkpoint: At 3-4 minute mark, look for golden brown crust before flipping

Step 4: How Do You Know When It Is Done?

Internal temperature determines doneness. Pull the steak 5 degrees before your target.

Instructions:

1. Insert instant-read thermometer into thickest part of steak
2. Remove at 125 degrees F for medium rare (will rise to 130-135 degrees F while resting)
3. Rest steak on cutting board for 5-10 minutes before slicing

Target Temperature: 125 degrees F (remove from heat) for medium rare finish

Visual Indicator: Deep brown crust, steak feels like the base of your thumb when you touch your thumb to middle finger

Method 2: Outdoor Grill

Grilling takes 8-12 minutes for a 1-inch thick top sirloin steak. You get charred grill marks and smoky flavor.

This method handles multiple steaks at once. Great for feeding a crowd.

Step 1: How Do You Prepare the Sirloin for Grilling?

Prep is nearly identical to pan searing. Room temperature and dry surfaces are key.

Instructions:

1. Remove steaks from fridge 30 minutes before grilling
2. Pat completely dry and season with salt and pepper
3. Brush lightly with oil to prevent sticking

Equipment: Grill brush, tongs, meat thermometer, oil

Step 2: What Grill Temperature and Time Do You Use?

High heat for direct grilling gives the best results on sirloin.

Instructions:

1. Preheat grill to 450-500 degrees F with lid closed
2. Clean and oil the grates
3. Place steaks over direct heat

Temperature: 450-500 degrees F

Time: 4-5 minutes per side for medium rare on a 1-inch steak

Step 3: When Do You Flip on the Grill?

Flip once at the halfway point. Rotate 45 degrees on each side for crosshatch grill marks if you want them.

Instructions:

1. Grill first side for 4-5 minutes without moving
2. Flip and grill another 4-5 minutes
3. Brush with melted garlic herb butter during the last minute

Checkpoint: Grill marks should be dark brown before flipping

Step 4: How Do You Know When the Grilled Steak Is Done?

Always verify with a meat thermometer. Grill temperatures vary.

Instructions:

1. Check internal temperature at thickest part
2. Remove at 125 degrees F for medium rare
3. Rest 5-8 minutes before serving

Target Temperature: 125 degrees F (will rise to 130-135 degrees F)

Visual Indicator: Char marks, juices pooling on surface

Method 3: Air Fryer

Air frying takes 10-14 minutes at 400 degrees F. You get even browning with almost no cleanup.

This method works best for 1-2 steaks depending on basket size. Quick option for weeknight beef sirloin dinners.

Step 1: How Do You Prepare for Air Frying?

Same prep as other methods. Dry steaks brown better.

Instructions:

1. Let steaks sit at room temperature for 30 minutes
2. Pat dry with paper towels
3. Brush lightly with olive oil on all sides
4. Season with salt and pepper

Equipment: Air fryer, meat thermometer, tongs

Step 2: What Air Fryer Temperature and Time Do You Use?

Preheat the air fryer before adding the steak. Hot air circulation creates the sear.

Instructions:

1. Preheat air fryer to 400 degrees F for 3-5 minutes
2. Place steak in basket without overlapping
3. Cook for 5-7 minutes per side

Temperature: 400 degrees F

Time: 10-14 minutes total for medium rare on a 1-inch steak

Step 3: When Do You Flip in the Air Fryer?

Flip once at the halfway point for even browning.

Instructions:

1. Flip steak at 5-7 minutes
2. Continue cooking until desired internal temperature

Checkpoint: Check for browning at 5-minute mark

Step 4: How Do You Know When the Air Fried Steak Is Done?

The meat thermometer is your best friend here.

Instructions:

1. Insert thermometer into center of steak
2. Remove at 125-130 degrees F for medium rare
3. Top with butter and rest 5 minutes

Target Temperature: 125-130 degrees F

Visual Indicator: Browned exterior, firm but springy when pressed

Method 4: Reverse Sear

Reverse searing takes 45-60 minutes total but delivers edge-to-edge pink with a deep crust. Best method for thick cut sirloin steaks over 1.5 inches.

Start low in the oven and finish hot in a pan. Worth the extra time for special occasions.

Step 1: How Do You Prepare for Reverse Searing?

Season the steak ahead of time. Salt draws moisture to the surface then reabsorbs it.

Instructions:

1. Season steak generously with salt 45 minutes to 1 hour before cooking
2. Place on wire rack set over baking sheet
3. Let sit uncovered at room temperature

Equipment: Wire rack, baking sheet, oven, cast iron skillet, meat thermometer

Step 2: What Oven Temperature and Time Do You Use?

Low heat brings the steak up slowly and evenly.

Instructions:

1. Preheat oven to 225-275 degrees F
2. Place steak on wire rack in center of oven
3. Cook until internal temp reaches 110-115 degrees F (30-45 minutes)

Temperature: 225-275 degrees F

Time: 30-45 minutes in oven, plus 2-3 minutes for the sear

Step 3: When Do You Sear the Steak?

Sear immediately after removing from the oven. Have your pan screaming hot.

Instructions:

1. Preheat cast iron skillet until smoking while steak finishes in oven
2. Add oil and sear steak 45-60 seconds per side
3. Flip every 30 seconds for 2-3 minutes total if you prefer

Checkpoint: Internal temp of 110-115 degrees F signals time to sear

Step 4: How Do You Know When the Reverse Seared Steak Is Done?

The sear finishes the cooking. Watch your thermometer.

Instructions:

1. Check temp after searing both sides
2. Target 125-130 degrees F for medium rare
3. Rest 5 minutes (less carryover cooking with this method)

Target Temperature: 125-130 degrees F after searing

Visual Indicator: Deep brown crust, even pink throughout when sliced

Safety and Quality Indicators

Food Safety:

• Internal Temperature: 145 degrees F minimum per USDA for whole beef steaks, though many prefer 130-135 degrees F for medium rare
• Resting: Always rest steak 5-10 minutes before cutting
• Storage: Refrigerate raw steak within 2 hours of purchase

Quality Indicators (Done Properly):

• Color: Deep brown crust outside, pink to red center depending on doneness
• Texture: Firm but springy when pressed, not mushy or rock hard
• Temperature: 130-135 degrees F internal for medium rare
• Appearance: Juices pool on surface during rest, not running out when cut

Signs of Overcooking:

• Gray color throughout with no pink
• Tough, chewy texture
• Dry, stringy meat fibers
• Internal temp over 160 degrees F

Serving Suggestions

Portion Size: 6-8 oz per person (2-3 servings per pound)

Serving Ideas:

• Slice against the grain and fan across the plate with compound butter
• Serve whole with a side of chimichurri sauce
• Slice thin for steak salad or fajitas

Pairing Recommendations:

• Baked potato or Costco mashed potatoes
• Grilled asparagus or roasted Costco frozen vegetables
• Side of Costco garlic bread
• Costco jasmine rice for a stir fry style meal

Storage and Reheating

Leftover Storage:

• Refrigerate within 2 hours of cooking
• Store in airtight container
• Consume within 3-4 days

Reheating Instructions:

• Oven: 250 degrees F for 10-15 minutes until warmed through
• Air Fryer: 350 degrees F for 3-5 minutes
• Skillet: Low heat with butter for 2-3 minutes per side
• Target Temperature: 110-120 degrees F to avoid overcooking

Troubleshooting Common Issues

Issue: Steak is tough and chewy

Cause: Overcooked past medium, or sliced with the grain instead of against it

Solution: Use a meat thermometer and pull steak at 125 degrees F for medium rare. Always slice against the visible muscle fibers.

Issue: No crust or sear on the outside

Cause: Pan was not hot enough, or steak surface was wet

Solution: Heat cast iron until smoking before adding steak. Pat steak completely dry with paper towels before seasoning.

Issue: Steak is dry inside

Cause: Cooked too long or at wrong temperature, or did not rest before cutting

Solution: Remove steak 5 degrees before target temp. Rest for 5-10 minutes so juices redistribute throughout the meat.

Issue: Uneven cooking (gray outside, raw center)

Cause: Steak was too cold when it hit the pan, or pan temperature was too high

Solution: Let steak sit at room temperature for 30 minutes before cooking. Use the reverse sear method for steaks over 1.5 inches thick.

Product Variations and Related Items

Similar Costco Beef Products:

• Costco filet mignon – More tender, less beefy flavor, higher price
• Costco ribeye cap steak – More marbling, richer taste
• Costco tri tip – Similar price point, best sliced thin
• Costco prime beef – Higher grade with more marbling

Cooking Time Adjustments:

• 1-inch steak: 8-10 minutes total
• 1.5-inch steak: 12-15 minutes total
• 2-inch steak: Use reverse sear method, 45-60 minutes total

Which Method Should You Choose?

Choose Cast Iron when:

• You want the best sear and crust
• Cooking 1-2 steaks
• You have 15 minutes and a ventilated kitchen

Choose Grill when:

• You want smoky flavor and grill marks
• Cooking for multiple people
• Weather permits outdoor cooking

Choose Air Fryer when:

• You want minimal cleanup
• Cooking 1-2 steaks quickly
• You do not have outdoor grill access

Choose Reverse Sear when:

• Your steak is over 1.5 inches thick
• You want perfect edge-to-edge doneness
• You have 45-60 minutes

Time Comparison: Air Fryer (10-14 min) is similar to Cast Iron (8-12 min) and Grill (8-12 min). Reverse Sear takes longest (45-60 min).

Texture Ranking: Cast Iron (best crust) and Reverse Sear (most even doneness) tie for top spot. Grill adds smoky flavor. Air Fryer is easiest with good results.

FAQ on How To Cook Costco Top Sirloin

What temperature should I cook Costco top sirloin steak?

For medium rare, pull the steak at 125 degrees F internal temperature. It will rise to 130-135 degrees F while resting.

Use an instant-read meat thermometer for accuracy. Grill or pan temperature should be 450-500 degrees F for proper searing.

How long do you cook top sirloin steak on each side?

A 1-inch thick sirloin steak needs 3-4 minutes per side in a hot cast iron skillet.

Thicker cuts require more time. For 1.5-inch steaks, cook 5-6 minutes per side or use the reverse sear method.

Should I marinate Costco top sirloin before cooking?

Marinating is optional. Top sirloin has good beef flavor on its own.

If you marinate, use an acidic mixture for 30 minutes to 2 hours max. Longer marinating turns the meat mushy and affects texture.

Why is my sirloin steak tough and chewy?

Overcooking is the main cause. Sirloin becomes tough when cooked past medium doneness.

Other causes include not resting the meat before slicing and cutting with the grain instead of against it.

What is the difference between USDA Choice and Prime sirloin at Costco?

Prime grade has more marbling than Choice. This means more intramuscular fat and a richer taste.

Prime costs about $2 more per pound. For top sirloin specifically, many find the difference subtle compared to ribeye.

Can I cook Costco top sirloin from frozen?

Yes, but results are better with thawed beef. Frozen steaks take 50% longer to cook.

Thaw in the refrigerator for 24 hours. Never thaw at room temperature or use a microwave for steak.

How do I get a good sear on sirloin steak?

Three things matter: dry surface, hot pan, and patience.

Pat the steak completely dry with paper towels. Heat your cast iron skillet until smoking. Do not move the steak for 3-4 minutes.

What is the best way to season Costco top sirloin?

Simple works best. Kosher salt and black pepper are all you need.

Season 30-45 minutes before cooking for dry brining. Add garlic, rosemary, and butter basting during the last minute of cooking.

How long should sirloin steak rest after cooking?

Rest the steak for 5-10 minutes before slicing. This allows juices to redistribute throughout the meat.

Tent loosely with foil. Cutting too early causes juices to run out onto the plate instead of staying in the beef.

Is top sirloin a good cut of steak?

Top sirloin offers solid beef flavor at an affordable price. It sits between budget cuts and premium options like ribeye.

The meat is leaner with less marbling. Proper cooking technique matters more with this cut to keep it tender and juicy.

Conclusion

Learning how to cook Costco top sirloin comes down to a few basics. High heat, dry surface, and a reliable meat thermometer get you there every time.

This Kirkland Signature beef delivers solid results whether you use a cast iron skillet, grill, or air fryer.

Pull the steak at 125 degrees F for medium rare. Let it rest. Slice against the grain.

Top sirloin proves you do not need expensive cuts for a tender juicy steak on a weeknight. Simple seasoning and proper technique make all the difference.