Cut the beef and vegetables into bite-sized pieces.
In a bowl, mix soy sauce, sesame oil, minced garlic, and sugar to make the marinade.
Marinate the beef and vegetables in the sauce for 10 minutes.
Heat cooking oil in a pan and stir-fry the marinated ingredients over high heat.
Once all the ingredients are cooked and glossy, turn off the heat.
Transfer to a plate and sprinkle with sesame seeds to finish.