In a medium bowl, combine all ingredients for the sauce.
To a large zip-top bag add the chicken and the sauce. Seal bag, move contents around to coat the chicken evenly, and place the bag in the fridge to marinate for at least 30 minutes (overnight is best).
Preheat oven to 475F and line a baking sheet with foil sprayed with non-stick spray for easy clean up.
To the baking sheet, add the pineapple, snow peas, onion, and bell pepper. Drizzle with 2 tablespoons olive oil, and season with salt and pepper to taste.
Remove the chicken from the bag with tongs or a fork (discarding marinade) and place it on the baking sheet. Move around/toss using tongs with the veggies. Spread evenly around the baking sheet making a single layer.
Bake for about 15 minutes (stirring halfway through) or until chicken is cooked through. Because of the natural sugars in this recipe keep an eye on the baking sheet. The chicken (in small pieces) and the sweet pineapple can easily burn. I would start checking between 8-10 minutes.
Remove from the oven and let rest for 2-3 minutes. Garnish with sliced green onions and sesame seeds if desired. Serve with rice if desired.