Slice the beef thinly.
Julienne the onion, carrot, and green onion.
Mix soy sauce, sugar, minced garlic, sesame oil, pepper, and pear juice to make the marinade.
Add the marinade to the beef and let it sit for 20 minutes.
Heat oil in a pan and stir-fry beef and vegetables.
Once the beef is cooked, transfer to a plate and serve.