Whisk together soy sauce, brown sugar, grated apple, grated onion, mirin, garlic, ginger, sesame oil, and pepper for bulgogi sauce.
Heat oil in large skillet over medium-high heat and brown ground beef, breaking into small pieces.
Drain excess fat if more than 2 Tbsp remains.
Pour bulgogi sauce over beef and simmer 3-4 minutes until liquid evaporates and beef caramelizes.
Remove from heat and set aside.
Whisk together gochujang, sesame oil, soy sauce, mirin, garlic, and brown sugar.
Cook ramen noodles according to package instructions and drain well.
Toss hot noodles with gochujang sauce until evenly coated.
Transfer noodles to bowls and top with bulgogi beef.
Garnish with cilantro, green onions, and sesame seeds.