In a medium bowl, whisk together soy sauce, mirin, honey, sesame oil, minced garlic, and grated ginger to create the teriyaki marinade.
Add beef cubes to the marinade, ensuring all pieces are well-coated. Cover and refrigerate for 1–2 hours for maximum flavor.
If using wooden skewers, soak them in water for at least 30 minutes to prevent burning.
Thread marinated beef cubes onto skewers, leaving a small gap between each piece.
Preheat a grill or broiler to medium-high heat. Lightly oil the grill grates or baking sheet.
Place skewers on the grill or under the broiler. Cook for 4–6 minutes per side, depending on desired doneness, basting occasionally with leftover marinade.
Remove skewers from heat and sprinkle with sesame seeds and sliced green onions if desired.
Serve immediately while hot and juicy.