Slice the beef thinly.
Make a marinade by mixing soy sauce, sugar, minced garlic, sesame oil, and black pepper.
Marinate the beef in the sauce for 30 minutes.
Heat oil in a pan and stir-fry onion and green onions.
Add the marinated beef and stir-fry.
Add carrots and mushrooms and cook together.
Finish by sprinkling sesame seeds on top.