In a medium bowl, whisk together soy sauce, brown sugar, sesame oil, minced garlic, freshly grated ginger, and rice vinegar until combined. Add the boneless, skinless chicken thighs, ensuring they're well-coated in the marinade. Cover the bowl and let the chicken marinate in the refrigerator for at least 15 minutes.

While the chicken marinates, cook your rice according to package instructions.

Heat a grill pan or large skillet over medium-high heat. Once hot, add the marinated chicken thighs, reserving the marinade for later. Sear the chicken for about 5-7 minutes on each side, or until cooked through. Remove and let rest before slicing.

In the same pan, sauté broccoli, julienned carrots, and sliced red bell peppers for 3-4 minutes until tender yet crisp.

In individual serving bowls, spoon a generous portion of fluffy rice. Layer on the sliced grilled chicken and sautéed vegetables artfully.

Sprinkle chopped green onions and sesame seeds on top. Drizzle with Sriracha as desired, and serve hot.