In a bowl, combine soy sauce, brown sugar, sesame oil, rice vinegar, garlic, and ginger. Add the boneless chicken thighs, ensuring they're well-coated, cover the bowl, and let them marinate for at least 15 minutes (up to 2 hours for a more robust flavor).

Cook your choice of rice according to the package instructions, aiming for a fluffy texture.

Preheat your grill or pan to medium heat. Remove chicken from the marinade (discard the marinade) and grill the thighs for 6-7 minutes on each side until juices run clear.

In the last few minutes of grilling the chicken, add the broccoli florets to the grill and cook them until tender, about 3-4 minutes.

Spoon the cooked rice into bowls. Top each bowl with grilled chicken, broccoli, julienned carrots, and cucumber. Garnish with chopped green onions and a sprinkle of sesame seeds.

Optional: Add a fried egg on top for a richer flavor.