Prepare the beef: If not pre-sliced, thinly slice beef against the grain. Pat dry with paper towels for better caramelization.
Make the marinade: In a bowl, combine soy sauce, brown sugar, sesame oil, rice wine/mirin, grated pear/apple, garlic, ginger, black pepper, and green onions. Mix well until sugar is dissolved.
Marinate the beef: Add beef slices to the marinade. Toss to coat evenly and let marinate for at least 30 minutes at room temperature or 2–4 hours in the refrigerator for deeper flavor.
Cook the beef: Heat vegetable oil in a large skillet or grill pan over medium-high heat. Add marinated beef in a single layer (cook in batches if necessary). Sear for 2–3 minutes per side until beef is cooked through and slightly caramelized.
Prepare steamed rice: While cooking the beef, steam or cook rice according to package instructions until fluffy.
Serve: Serve bulgogi hot over steamed rice. Optional: Garnish with sesame seeds and extra sliced green onions. Optional: Serve with lettuce leaves and kimchi for authentic Korean-style wraps.