Cowboy Butter Green Bean Flank Steak Crockpot Dinner

This is the set-it-and-forget-it dinner that delivers big flavor with almost no effort. Thin slices of flank steak, fresh green beans, and russet potatoes cook low and slow in a bath of garlic-herb cowboy butter and savory au jus.

The result is a velvety, rich, and deeply satisfying meal that tastes like it simmered all day — because it did. Serve it over creamy mashed potatoes and watch everyone ask for seconds.

This Crockpot recipe is the definition of easy weeknight cooking. You simply layer raw flank steak strips, green beans, and diced potatoes in the slow cooker, top with slices of garlic-herb butter and a packet of au jus mix, then cover and walk away.

Hours later, you're greeted by a bubbling pot of tender beef, soft vegetables, and a glossy, buttery gravy that coats every bite. It's a complete dinner that needs just one pot and minimal prep.

Ingredients

Why this recipe works

The slow cooker does all the work here. Low, gentle heat breaks down the connective tissue in flank steak, turning a naturally lean cut into fork-tender strips that practically melt in your mouth. Cooking the vegetables alongside the beef means they absorb the savory beef and butter flavors as they soften, creating a cohesive, deeply seasoned dish.

The combination of garlic-herb cowboy butter and au jus mix creates a rich, savory gravy without any extra steps. The butter melts into the juices, adding richness and body, while the au jus seasoning provides a salty, beefy backbone.

Because everything cooks together in one pot, the flavors meld and concentrate, giving you a complex sauce with zero stirring or deglazing.

Notes and substitutions

Flank steak is the star here — it's lean but becomes wonderfully tender when cooked low and slow. Slice it thinly against the grain before cooking to help it break down even faster. If flank steak isn't available, sirloin or chuck roast work well; just cut them into similar thin strips.

For the green beans, fresh ones hold their texture best, but frozen (thawed) green beans can be substituted — just reduce the cook time by about an hour.

Russet potatoes are ideal because they soften and absorb the gravy, but Yukon Gold or red potatoes are also excellent. The garlic-herb cowboy butter is a shortcut; if you don't have it, mix softened butter with minced garlic and dried herbs.

• flank steak: sirloin steak or chuck roast, thinly sliced
• fresh green beans: frozen green beans, thawed (reduce cook time by 1 hour)
• russet potatoes: Yukon Gold or red potatoes, diced
• garlic-herb cowboy butter: 4 tablespoons unsalted butter mixed with 2 minced garlic cloves and 1 teaspoon dried herbs

Equipment

• 6-quart slow cooker
• Cutting board
• Chef's knife
• Measuring spoons
• Serving spoon