Combine soy sauce, sugar, minced garlic, and sesame oil in a bowl to make the marinade.
Add the thinly sliced beef to the marinade, ensuring all pieces are well coated. Leave it to marinate for at least an hour, or overnight for best results.
Heat a pan or grill over high heat. Add the marinated beef and cook until it's nicely browned and cooked through, about 3-5 minutes.
Notes
Make sure to slice the beef as thinly as possible for the best absorption of flavors and quick cooking.
Marinating the meat overnight will make it more flavorful and tender.
A hot pan or grill is key to getting a nice sear on the beef, enhancing its flavor.
Don't overcrowd the pan when cooking the beef. Cook in batches if necessary to avoid steaming the meat.
Feel free to add in vegetables like thinly sliced onions or bell peppers for extra flavor and texture.