For a hands-off approach, try this Slow Cooker Mongolian Beef recipe. The beef is sliced using a food processor and then cooked in a flavorful sauce made with soy sauce, brown sugar, garlic, and ginger. Let it simmer in the slow cooker for several hours until the beef is tender and the flavors have melded together. Serve it over rice or noodles for a comforting and delicious meal.