Slow Cooker Sour Cream Mushroom Flank Steak

This slow cooker flank steak is the definition of set-it-and-forget-it comfort food. You just layer a few pantry staples over the beef, walk away, and hours later you have a rich, creamy mushroom gravy with meat so tender it falls apart. Serve it over buttery egg noodles for a dinner that feels like a hug.

This recipe takes the classic flavors of beef stroganoff and turns them into an effortless slow cooker meal. Thinly sliced flank steak simmers low and slow in a sauce made from condensed mushroom soup, sour cream, and brown gravy mix, with sweet onions and mushrooms throughout.

The result is a velvety, savory gravy that clings to every noodle. It's the kind of dinner that makes the whole house smell amazing and requires almost zero hands-on time.

Ingredients

Why this recipe works

The slow cooker does all the work here. Cooking the flank steak on low heat for several hours breaks down the connective tissue, turning a lean cut into fork-tender bites. The gentle heat also allows the flavors of the soup, gravy mix, and sour cream to meld into a single, cohesive sauce that coats every piece of meat.

Using condensed cream of mushroom soup as the base is a clever shortcut. It's already thickened and seasoned, so it creates a rich gravy without any extra steps.

The brown gravy mix adds depth and color, while the sour cream stirred in at the end gives the sauce its signature tangy creaminess. This method is foolproof and perfect for busy weeknights.

Notes and substitutions

Flank steak is the star here, but you can also use sirloin or chuck roast. Slice it thinly against the grain before cooking for the most tender results.

If you prefer a thicker cut, just increase the cooking time slightly. The onions and mushrooms add texture and savoriness, but you can adjust the amounts to your liking.

Use full-fat sour cream for the best texture; low-fat versions can curdle more easily. The brown gravy mix is essential for that deep, beefy flavor — look for it in the gravy aisle.

If you need a gluten-free option, check labels carefully and use a gluten-free gravy mix and noodles. This recipe is naturally nut-free and can be made dairy-free with substitutions.

• flank steak: sirloin steak or chuck roast, thinly sliced
• cream of mushroom soup: cream of chicken soup (omit if dairy-free; use a dairy-free cream soup alternative)
• sour cream: plain Greek yogurt or a dairy-free sour cream substitute
• brown gravy mix: 1 tablespoon beef bouillon powder plus 1 tablespoon cornstarch

Equipment

• 6-quart slow cooker
• Cutting board
• Chef's knife
• Measuring cups and spoons
• Large pot for noodles
• Serving spoon