Cowboy Butter Sirloin Tips and Potatoes: Slow Cooker Step-by-step instructions

Before you start

Before starting, cut the sirloin tips into 2-inch pieces if they aren't already. Halve the baby potatoes so they cook evenly. Mince the garlic if using fresh. Soften the cowboy butter if it's straight from the fridge. Have the au jus mix packet open and ready.

A 6-quart slow cooker is ideal for this recipe; if using a smaller one, reduce the quantities slightly. No need to brown the meat first—the slow cooker does all the work, and skipping that step keeps prep to just a few minutes.

Instructions

Layer and Cook Low

1. 1Layer the Ingredients
   Place the sirloin steak tips in the bottom of a 6-quart slow cooker. Scatter the halved baby Yukon Gold potatoes and minced garlic over and around the beef. Place the two sticks of garlic-herb cowboy butter on top, then sprinkle the au jus mix evenly over everything. Do not stir.
   Look for The butter and au jus mix sit on top of the meat and potatoes, ready to melt down.
   Tip Cut the potatoes into uniform halves so they cook evenly with the beef.
2. 2Cover and Cook Low
   Cover the slow cooker and cook on low for 6 to 7 hours, or until the beef is fork-tender and the potatoes are soft. The butter will melt and combine with the au jus to create a rich, savory gravy. Avoid opening the lid during cooking to keep the heat steady. Let it rest for 3 minutes before slicing.
   Look for The aroma of garlic and herbs fills the kitchen; the sauce is bubbling gently around the edges.
   Safe temperature 145°F (63°C) internal temperature (steaks, chops and roasts)
   Tip Low and slow is key for tender sirloin tips. If time is short, cook on high for 3 to 4 hours, but the texture will be less tender.

At the end of this phase, the slow cooker is filled with raw beef, potatoes, garlic, and butter. The butter is starting to melt, and the au jus mix is dissolving into the liquid. The aroma of garlic and herbs is just beginning to develop.

The mixture is not yet bubbling, but the slow cooker is heating up. Check that all ingredients are covered by the melting butter and au jus; if not, gently push them down with a spoon.

Tender and Fragrant

3. 3Check for Doneness
   After 6 hours, check the beef by piercing a piece with a fork. It should shred or cut easily. The potatoes should be fork-tender with no resistance. Use an instant-read thermometer to confirm the beef reaches 145°F (63°C) for medium-rare, or up to 160°F (71°C) for well done. Let the meat rest for at least 3 minutes before serving.
   Look for The beef is deeply browned and the potatoes are golden from the butter.
   Safe temperature 145°F (63°C) internal temperature (steaks, chops and roasts)
   Tip If the sauce seems thin, remove the beef and potatoes and simmer the liquid on the stovetop to reduce.
4. 4Rest the Meat
   Turn off the slow cooker and let the beef rest in the hot liquid for at least 3 minutes. This allows the juices to redistribute through the meat, keeping it moist and tender. Do not skip this step, even though the meat is already cooked.
   Look for The meat rests in the hot gravy, absorbing extra flavor.
   Tip Resting is especially important for lean cuts like sirloin to prevent dryness.

After 6 to 7 hours, the slow cooker is bubbling gently. The beef is visibly tender, and the potatoes are soft enough to be pierced easily. The sauce is a deep golden brown, rich with melted butter and au jus. The kitchen smells intensely of garlic and herbs. The beef should register at least 145°F (63°C) on an instant-read thermometer. The sauce may look slightly separated but will come together with a gentle stir.

Serve and Enjoy

5. 5Serve Over Mashed Potatoes
   Spoon the sirloin tips, potatoes, and plenty of the garlic-herb butter au jus over creamy whipped mashed potatoes on a plate. Serve immediately, with extra gravy spooned over the top.
   Look for The beef and potatoes are glossy with butter and au jus, steaming hot.
   Tip For a complete meal, add a side of green beans or a simple salad.

The final dish is a generous spoonful of sirloin tips, potatoes, and gravy served over creamy mashed potatoes. The beef is fork-tender and glistening with sauce. The potatoes are golden and buttery. The gravy is thick and coats the spoon. The plate is steaming hot and ready to eat. The flavors are rich, savory, and deeply satisfying, with the garlic and herbs shining through.

Common mistakes

A common mistake is lifting the lid to check on the food, which lets heat escape and extends cooking time. Resist the urge; trust the slow cooker. Another is using lean cuts like sirloin without enough fat, which can dry out—sirloin tips are ideal because they have some marbling.

Overcrowding the slow cooker can also lead to uneven cooking, so keep the ingredients in a single layer if possible. Finally, don't skip the resting period; it's essential for juicy meat.

How to tell it’s done

The dish is done when the beef is fork-tender and the potatoes are soft. Pierce a piece of beef with a fork; it should shred easily or cut with no resistance. The potatoes should offer no resistance when pierced.

For food safety, the beef must reach an internal temperature of at least 145°F (63°C) for medium-rare, but slow cooking typically brings it higher. Let the meat rest for at least 3 minutes before serving to allow the juices to redistribute. The sauce should be thick and glossy, coating the back of a spoon.

• Steaks, chops and roasts: 145°F (63°C) in the thickest part, then a 3-minute rest