Combine all of the Marinade ingredients in a blender and puree until completely smooth. Place Chicken in a zip-top bag, and pour in the Marinade. Toss the Chicken to coat all sides, and marinate for at least 1 hour and up to overnight
Preheat oven to 400°F.
Prepare a baking sheet lined with a wire rack. Arrange the Chicken on the rack and bake for 30 minutes or until the Chicken registers 160°F on a meat thermometer. About half way through the baking time remove excess fat from baking dish. Allow to rest for 10 minutes before serving.
While the Chicken bakes, combine the Avocado, Mango, Cilantro, and Scallions in a large bowl. Add the Lime Juice and Olive Oil with a pinch of Salt and a couple of cracks of Freshly Ground Pepper. Toss together and taste for seasoning.