Slice the beef eye of round thinly.
Julienne the onion and green onion.
Marinate the beef with soy sauce, minced garlic, black pepper, and sesame oil for 10 minutes.
Add oil to a pan and stir-fry the beef.
Add the onion and green onion and stir-fry together.
Once the beef and vegetables are cooked, transfer them to a plate.