In a mixing bowl, whisk together soy sauce, pineapple juice, brown sugar, honey, rice vinegar, sesame oil, garlic, ginger, and black pepper. Add the beef cubes, tossing them well to coat. Cover and let marinate in the fridge for at least 2 hours (or overnight for extra flavor).
Soak the Skewers
If using wooden skewers, soak them in water for 30 minutes to prevent burning on the grill.
Assemble the Kebabs
Thread the marinated beef onto skewers, alternating with bell peppers, onions, and pineapple chunks for a colorful, balanced skewer.
Grill to Perfection
Preheat your grill (or grill pan) to medium-high heat. Lightly oil the grates and grill the skewers for 8-10 minutes, turning occasionally, until the beef is slightly charred and cooked to your preferred doneness. Brush with extra marinade during grilling for extra flavor.
Garnish and Serve
Sprinkle with sesame seeds and chopped green onions. Serve hot with steamed rice, a side salad, or extra teriyaki sauce for dipping.