Step 1

Heat olive oil in a large skillet over medium-high heat. Add the beef and sprinkle with the salt and pepper. Cook until the beef is browned on all sides. Transfer beef to the slow cooker.

Step 2

Add the butter to the skillet. Once melted, add the onion and mushrooms. Cook, stirring often, until onion and mushrooms have softened, about 5 minutes.

Step 3

Add the garlic and flour and cook, stirring, for 30 seconds. Stir in the beef broth. Cook for 1-2 minutes, stirring and scraping up any browned bits from the bottom of the pan, until thickened. Transfer contents of the skillet to the slow cooker.

Step 4

Stir the Worcestershire sauce and dried thyme into the slow cooker.

Step 5

Cover and cook on low for 6-8 hours or high for 3-4 hours.

Step 6

Stir in the sour cream (or plain Greek yogurt). Taste and add more salt and pepper, if needed. Serve over egg noodles, mashed potatoes, rice, etc.