Slice the beef thinly.
Julienne the onion, green onion, and carrot.
Mix soy sauce, sugar, minced garlic, sesame oil, pepper, and pear juice to make the marinade.
Add the marinade to the beef and vegetables, and let it marinate for 20 minutes.
Heat oil in a pan and stir-fry the marinated beef bulgogi.
When the beef is cooked, turn off the heat.