Steps
1. In a small bowl, combine the soy sauce, sesame oil, garlic, and ginger.
2. Heat a wok or large skillet over medium heat, and add the vegetable oil.
3. Add the beef, and cook until evenly browned.
4. Add the bell peppers, carrots, mushrooms, and onion.
5. Pour in the soy sauce mixture, and cook for 3 to 5 minutes, stirring frequently.
6. Serve hot.