Cut the beef, chicken, and shrimp into bite-sized pieces.
Finely chop the onion, green onion, and bell pepper.
Heat cooking oil in a pan and stir-fry the beef, chicken, and shrimp.
Add the vegetables and stir-fry together.
Add cooked rice and stir-fry, mixing well with the ingredients.
Season with soy sauce and black pepper.
Transfer to a plate and serve.