Preheat oven to 350 F.
Place the vegetables on a large baking sheet and sprinkle with salt and pepper.
Place the chicken in a large plastic bag.
In a bowl, mix together the garlic, ginger, honey, ketchup, coconut sugar, rice wine vinegar, and tamari. Add ¼ cup of the sauce to the chicken and toss to combine.
Place the chicken on top of the vegetables, sprinkle with a pinch each of salt and pepper, and bake for 20 minutes.
Put the rest of the sauce into a saucepan over medium low heat.
Combine the water and cornstarch and add it to the sauce. Bring the sauce to a slight boil, then reduce the temperature to a medium low and simmer until it thickens, about 3-4 minutes.
Drizzle the chicken and vegetables with the rest of the sauce and bake for an additional 20 minutes, or until the chicken reaches 165 F.
Serve topped with sesame seeds and cilantro, if desired.