Pat the chicken breasts dry with paper towels. If thick, slice them horizontally to create evenly sized pieces. This ensures uniform cooking and prevents dryness.

In a large mixing bowl, whisk together low-sodium soy sauce, gochujang, minced garlic, grated ginger, rice vinegar, sesame oil, honey or sweetener, black pepper, and optional red chili flakes.

Add the chicken to the bowl and coat thoroughly with the marinade. Cover and refrigerate for at least 30 minutes. For best flavor, marinate for 2–8 hours.

Preheat your grill or grill pan to medium-high heat. Lightly oil the grates to prevent sticking.

Place the marinated chicken on the grill. Cook for 5–7 minutes per side, turning once, until grill marks appear and internal temperature reaches 165°F (74°C).

If desired, simmer leftover marinade in a small saucepan for 5 minutes to create a thicker glaze. Brush lightly over chicken during the final minute of grilling.

Remove chicken from the grill and let rest for 5 minutes. This allows juices to redistribute, keeping the meat tender.

Slice the chicken, garnish with green onions and sesame seeds, and serve immediately.