In a bowl, mix soy sauce, brown sugar, honey, minced garlic, grated ginger, sesame oil, and red pepper flakes together until well combined. Add the bite-sized steak pieces to the marinade, ensuring they are fully coated. Cover the bowl and let it marinate in the refrigerator for at least 15 minutes.
While the steak is marinating, heat a skillet over medium-high heat with a splash of oil to prevent sticking. Allow the pan to get hot enough so that when you add the steak bites, they begin to sizzle right away.
Once your pan is ready, add the marinated steak bites in a single layer without overcrowding them. Sear each side for about 2-3 minutes until they reach your desired level of doneness.
After cooking, transfer the steak bites to a serving platter immediately. Sprinkle generously with sliced green onions and sesame seeds before serving.