Cut the beef and mushrooms into bite-sized pieces
Slice vegetables such as onion and green onion
Season the beef with salt, pepper, and soy sauce
Add oil to the pan and stir-fry the beef
When the beef is half cooked, add mushrooms and vegetables and stir-fry
Add seasonings such as soy sauce, sugar, and sesame oil and continue stir-frying
Once all ingredients are cooked, turn off the heat and plate