Cowboy Butter Pepper Tenderloin Tips: Slow-Cooker Dinner Step-by-step instructions

Before you start

Before you start, make sure you have a slow cooker large enough to hold the ingredients comfortably—a 6-quart model works well. If your cowboy butter is frozen, let it soften slightly so it’s easy to place on top.

You’ll also want to have your serving dish ready and, if you plan to serve over mashed potatoes, prepare those just before the slow cooker is done. There’s no need to sear the beef or pre-cook the vegetables; everything goes into the slow cooker raw and comes out perfectly cooked.

Instructions

Layer and Walk Away

1. 1Layer the Ingredients
   Place the beef tenderloin tips in the bottom of the slow cooker. Scatter the green bell pepper strips, red bell pepper strips, and red onion wedges over the beef. Place the two sticks of garlic-herb cowboy butter on top of the vegetables, then sprinkle the dry au jus mix evenly over everything.
   Look for The beef is covered with peppers, onions, butter, and au jus mix.
   Tip No need to stir—the layers will meld as they cook.

At the end of this phase, the slow cooker contains raw beef, peppers, onions, butter, and au jus mix, all layered neatly. The butter will start to melt as the cooker heats, and the aroma of garlic and herbs will begin to fill the kitchen. This is the point where you cover the pot and let the magic happen.

Slow-Cook to Tender

2. 2Slow-Cook on Low
   Cover the slow cooker and cook on low for 6 to 8 hours, until the beef is fork-tender and the sauce is bubbling and rich. The butter will melt into the au jus, creating a golden gravy that coats the meat and vegetables. Let it rest for 3 minutes before slicing.
   Look for The sauce is bubbling gently, and the beef shreds easily with a fork.
   Safe temperature 145°F (63°C) internal temperature (steaks, chops and roasts)
   Tip Cooking on low keeps the tenderloin tips tender; high heat can toughen them.

After 6 to 8 hours, the sauce is bubbling gently, and the beef is fork-tender. The peppers and onions are soft and translucent, and the butter has fully melted into the au jus, creating a glossy, golden sauce. The kitchen smells rich and savory, and the beef is cooked through, reaching at least 145°F (63°C).

Rest and Serve

3. 3Rest and Serve
   Turn off the slow cooker. Let the beef rest in the sauce for at least 3 minutes before serving. Use a slotted spoon to transfer the beef and vegetables to a serving dish, then spoon the sauce over the top. Serve hot over mashed potatoes or with crusty bread.
   Look for The beef is tender, the peppers are soft, and the sauce is thick and glossy.
   Tip If the sauce seems thin, simmer it on the stovetop for a few minutes to reduce.

The slow cooker is turned off, and the beef rests in the hot sauce for at least 3 minutes. When you lift a piece of beef, it should hold together but easily pull apart.

The sauce is thick enough to coat the back of a spoon, and the vegetables are tender but not mushy. Serve immediately over mashed potatoes or with bread to soak up the sauce.

Common mistakes

One common mistake is cooking on high, which can make the beef tough and dry. Always use the low setting for the best texture. Another is lifting the lid too often to check on the food—this releases heat and extends cooking time.

Resist the urge to stir; the layers are intentional, and stirring can break up the beef. Finally, don’t skip the resting period. Cutting into the beef immediately can cause the juices to run out, leaving you with drier meat.

How to tell it’s done

The beef is done when it is fork-tender and reaches an internal temperature of at least 145°F (63°C) for medium-rare, though it will likely be higher after hours of cooking. The sauce should be bubbling and slightly thickened, and the peppers and onions should be soft and easily pierced with a fork.

Let the beef rest in the sauce for at least 3 minutes before serving to allow the juices to redistribute. If you prefer your beef more well-done, cook until it reaches 160°F (71°C) or higher.

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