In a large bowl, combine the sliced flank steak, soy sauce, sesame oil, ginger, garlic, honey, and red pepper flakes. Mix well and let marinate for at least 15 minutes. For best results, marinate for 1 hour in the refrigerator.
Preheat your oven to 425°F (220°C).
Spread the marinated beef on a large sheet pan in a single layer. Add the bell pepper, broccoli, and snap peas around the beef.
Roast in the preheated oven for 15-20 minutes, or until the beef is cooked through and the vegetables are tender-crisp.
Remove from the oven and sprinkle with sliced green onions and sesame seeds.
Serve hot over cooked rice or quinoa.