Sour Cream French Onion Flank Steak Crockpot Dinner

This slow cooker dinner brings together tender flank steak strips, sweet Vidalia onions, and a velvety sour cream gravy that tastes like it simmered all day—because it does. With just a few minutes of prep, you can set it and forget it, then come back to a comforting meal that pairs perfectly with buttered egg noodles. It's the kind of recipe that feels indulgent but is simple enough for a busy weeknight.

This Crockpot recipe is all about minimal effort and maximum flavor. Thinly sliced flank steak is layered with sweet onions, beef consommé, sour cream, and a packet of brown gravy mix, then left to cook low and slow until the meat is fork-tender and the sauce is rich and creamy.

The result is a dish that tastes like a French onion soup meets beef stroganoff, served over noodles for a hearty dinner that everyone will love.

Ingredients

Why this recipe works

The slow cooker does the heavy lifting here. Cooking the flank steak on low for several hours breaks down the connective tissue, turning a lean cut into meltingly tender strips.

The long, gentle heat also coaxes the natural sweetness out of the Vidalia onions, which soften into silky ribbons that infuse the gravy with deep flavor. The sour cream and brown gravy mix create a luscious, velvety sauce that clings to every bite.

Layering the ingredients without stirring is intentional. The consommé and sour cream create a moist environment that steams the beef and onions, while the gravy mix dissolves and thickens the liquid as it cooks.

This hands-off approach means you don't have to babysit the pot—just walk away and let the slow cooker work its magic. The result is a cohesive, richly flavored sauce that tastes like it simmered for hours, because it did.

Notes and substitutions

Flank steak is the star here, but you can also use sirloin or chuck if you prefer. Slice it thinly against the grain to ensure tenderness. Vidalia onions are sweet and mild, but any yellow onion will work; if you use a sharper onion, you might want to add a pinch of sugar to balance the flavor. Beef consommé adds a concentrated beefy taste—if you substitute broth, consider adding a little extra seasoning.

Sour cream should be full-fat for the best texture and richness. Low-fat versions can curdle slightly, but they still work in a pinch.

The brown gravy mix is a shortcut that adds savory depth and helps thicken the sauce; if you prefer to avoid packaged mixes, you can whisk together cornstarch and cold water at the end. Egg noodles are the classic accompaniment, but mashed potatoes or crusty bread are also great for soaking up the gravy.

• flank steak: sirloin steak or chuck roast, thinly sliced
• Vidalia onions: yellow onions or sweet onions
• beef consommé: beef broth (reduce salt if using broth)
• brown gravy mix: 1 tablespoon cornstarch mixed with 1/2 cup cold water, added at the end

Equipment

• Slow cooker (Crockpot)
• Large skillet or sauté pan
• Cutting board
• Chef's knife
• Measuring cups and spoons
• Mixing spoon
• Serving spoon
• Large pot for noodles