Slice the beef and onion thinly.
Cut the carrot and potato into bite-sized pieces.
Heat oil in a pan and stir-fry the beef.
Add the onion, carrot, and potato and stir-fry together.
Season with soy sauce, sugar, and cooking wine.
Pour in water and simmer over medium-low heat until the ingredients are cooked.
Finish with pepper and green onion.