Cowboy Butter Pepper Tenderloin Tips: Slow-Cooker Dinner

This is the dinner that practically makes itself: beef tenderloin tips, sweet peppers, red onions, and a generous amount of garlic-herb cowboy butter, all left to simmer in a slow cooker until the meat is impossibly tender and the sauce is rich and glossy.

The combination of savory beef, mellow roasted peppers, and the aromatic butter-infused au jus is pure comfort in a bowl. Serve it over mashed potatoes for a meal that feels special but requires almost no effort.

There are slow cooker recipes, and then there are slow cooker recipes that become part of your regular rotation. This one starts with trimmed beef tenderloin tips—already tender, but made even more succulent by hours of gentle cooking.

The bell peppers and red onions soften into sweet, silky strands, while the cowboy butter melts into the au jus, creating a golden, herb-flecked sauce that’s impossible to resist. The result is a hearty, satisfying dinner that tastes like you spent hours at the stove, when you actually just dumped everything into the Crockpot and walked away.

Ingredients

Why this recipe works

The beauty of this recipe lies in its simplicity. The beef tenderloin tips are a naturally tender cut, and the slow cooker’s low, moist heat breaks down any remaining connective tissue, leaving the meat fork-tender.

The cowboy butter—a blend of butter, garlic, herbs, and spices—melts into the au jus, enriching the sauce and coating every piece of beef and vegetable with flavor. Because the ingredients are layered without stirring, the flavors meld and develop as they cook, creating a depth that’s hard to achieve with quicker methods.

The high fat and moisture content of the butter and au jus keep the beef moist and prevent it from drying out, even after hours of cooking. The peppers and onions release their natural juices, which mingle with the sauce and add a subtle sweetness that balances the savory, umami-rich beef. This is a set-it-and-forget-it meal that delivers restaurant-quality results with minimal effort—perfect for busy weeknights or lazy weekends.

Notes and substitutions

Beef tenderloin tips are the star here, but you can substitute sirloin tips or even stew meat if you prefer. The key is to use a cut that benefits from low, slow cooking.

The cowboy butter is often sold in logs or tubs at the grocery store; if you can’t find it, make your own by mixing softened butter with garlic, parsley, chives, and a pinch of smoked paprika. The dry au jus mix is widely available and adds a savory, beefy depth—use a good-quality brand for the best flavor.

This recipe is incredibly forgiving. You can add more or fewer peppers, swap the red onion for a yellow one, or toss in mushrooms if you like. The slow cooker does all the work, so there’s no need to brown the beef first—though you can if you want extra color and flavor. Just remember to cook on low for the most tender results, and don’t skip the resting time before serving, as it allows the juices to redistribute.

• beef tenderloin tips: beef sirloin tips or beef stew meat (cut into 1-inch pieces)
• garlic-herb cowboy butter: 4 tbsp unsalted butter mixed with 2 tsp garlic powder, 1 tsp dried parsley, 1 tsp dried chives, and 1/2 tsp smoked paprika
• dry au jus mix: 1 cup beef broth mixed with 1 tsp Worcestershire sauce and 1/2 tsp onion powder
• green or red bell pepper: any color bell pepper or 1 cup sliced mushrooms

Equipment

• Slow cooker (6-quart or larger)
• Cutting board
• Chef's knife
• Measuring spoons
• Serving spoon
• Mashed potatoes for serving (optional)