01 - Whisk together soy sauce, brown sugar, sesame oil, garlic, pear, ginger, rice vinegar, and black pepper in a bowl. Add sliced ribeye and coat thoroughly. Let marinate for 15-30 minutes at room temperature.
02 - Heat a large skillet over medium-high heat. Add marinated beef in a single layer and cook for 3-4 minutes, stirring occasionally, until browned and cooked through. Transfer beef to a plate and set aside.
03 - Add a splash of oil to the same skillet if needed. Sauté onions and bell peppers for 2-3 minutes until softened and slightly translucent. Add chopped kimchi and stir-fry for 2 minutes until fragrant.
04 - Return cooked beef to the skillet. Toss everything together and heat through for 1-2 minutes, ensuring all components are well combined and hot.
05 - Preheat your broiler. Split hoagie rolls open and place cut side up on a baking sheet. Lightly toast under the broiler for 1-2 minutes until golden and crisp.
06 - Spoon the bulgogi-kimchi mixture evenly onto the toasted rolls. Top each sandwich with 2 slices of provolone cheese. Return to broiler for 1-2 minutes until cheese is melted, bubbly, and slightly browned.
07 - Sprinkle scallions and sesame seeds over the melted cheese. Spread with gochujang or mayonnaise if desired. Serve immediately while hot and cheesy.