Beef and Mushroom Skillet with Savory Pan Sauce -

This beef and mushroom skillet with savory pan sauce is the kind of cozy, one-pan dinner that feels restaurant-worthy but cooks up fast on a weeknight. You get tender seared beef, deeply browned mushrooms, and a silky sauce that begs for mashed potatoes, egg noodles, or crusty bread.

Why You’ll Love This Skillet Dinner

One pan, big flavor: The fond (browned bits) becomes the base of the pan sauce.
Fast and flexible: Works with sirloin, flank steak, or even stew meat sliced thin.
Comfort-food pairing friendly: Perfect over potatoes, rice, noodles, or with roasted veggies.

Ingredients

1 1/4 lb beef sirloin (or flank steak), sliced into 1/2-inch strips
1 tsp kosher salt, plus more to taste
1/2 tsp black pepper
1 1/2 tbsp all-purpose flour
2 tbsp olive oil, divided
3 tbsp unsalted butter, divided
12 oz cremini mushrooms, sliced
1 small yellow onion, thinly sliced
3 cloves garlic, minced
2 tsp Dijon mustard
1 tbsp Worcestershire sauce
1/2 cup dry beef broth (or stock)
1/2 cup low-sodium chicken broth (or more beef broth)
1/3 cup sour cream (or heavy cream)
1 tsp fresh thyme leaves (or 1/3 tsp dried thyme)
1 tbsp chopped fresh parsley (optional)

How to Make Beef and Mushroom Skillet with Savory Pan Sauce

1) Prep the beef. Pat the beef dry. Season with salt and pepper, then toss with flour until lightly coated. This helps with browning and gives the sauce a little body.

2) Sear the beef. Heat a large skillet (12-inch is ideal) over medium-high heat. Add 1 tbsp olive oil and 1 tbsp butter. When hot, sear the beef in a single layer (work in batches if needed) for about 1–2 minutes per side until browned but not overcooked. Transfer to a plate.

3) Brown the mushrooms. Reduce heat to medium. Add remaining 1 tbsp olive oil and 1 tbsp butter. Add mushrooms and spread them out. Let them cook undisturbed for 3–4 minutes to develop color, then stir and continue cooking 3–4 minutes more until nicely browned.

4) Add onion and garlic. Stir in sliced onion and cook 2–3 minutes until softened. Add garlic and thyme and cook 30 seconds until fragrant.

5) Build the pan sauce. Stir in Dijon and Worcestershire. Pour in broths and scrape up the browned bits from the bottom of the skillet. Simmer 3–5 minutes until slightly reduced.

6) Finish creamy and return beef. Reduce heat to low. Stir in sour cream until smooth (avoid boiling once it’s in). Add the beef back to the skillet along with any juices and warm through for 1–2 minutes. Taste and adjust salt and pepper. Swirl in the remaining 1 tbsp butter for extra gloss (optional but great).

Tips for the Best Results

Don’t crowd the pan: Brown the beef in batches so it sears instead of steaming.
Brown the mushrooms deeply: Color equals flavor. Give them time without stirring.
Keep sour cream gentle: Add it on low heat and don’t let the sauce boil to prevent curdling.
Want it thicker? Simmer a minute longer before adding sour cream, or add a splash less broth.

Serving Ideas

Mashed potatoes or buttery egg noodles
Steamed rice or cauliflower rice
Roasted green beans, broccoli, or a simple side salad
Crusty bread to mop up the sauce

Storage and Reheating

Refrigerate: Store leftovers in an airtight container for up to 3 days.
Reheat: Warm gently in a skillet over low heat with a splash of broth to loosen the sauce. Avoid boiling.
Freeze: Creamy sauces can separate after freezing, but it’s still workable. Freeze up to 2 months, thaw overnight, and reheat slowly while stirring.