Step 3: Build the Slow Cooker - Transfer the browned beef to the bottom of a
6 quart slow cooker. Scatter the diced onion and sliced mushrooms over the beef, then sprinkle the minced garlic across the top. Add the cream of mushroom soup, beef broth, Worcestershire sauce, and Dijon mustard. Stir everything together until the soup and broth are combined and the vegetables are nestled into the sauce.