This Mongolian beef stir-fry recipe is a quick and easy weeknight meal that can be made in your Thermomix. Thinly sliced beef is marinated in a mixture of soy sauce, sesame oil, and cornstarch, which helps to tenderize the meat and create a delicious glaze. The beef is then stir-fried with vegetables like bell peppers and onions until everything is cooked to perfection. Serve it over rice or noodles for a satisfying meal.