MARINADE: Whisk together all of the marinade ingredients in a medium-sized bowl: 3/4 cup orange juice, 1/2 cup olive oil, 1/3 cup lime juice, 1 teaspoon lime zest, honey, 1 teaspoon each cumin, soy sauce, garlic, and 1/4 cup cilantro. Add salt and pepper to taste (I use about 1 teaspoon salt and 1/4 teaspoon pepper). Reserve about 1/2 cup of marinade, and pour the rest into a large resealable bag.
Trim the chicken of fat. Pound the breasts to even thickness or slice in half to get evenly sized breasts and place in the bag with the rest of the marinade. Refrigerate for at least 30 minutes, making sure to flip the bag halfway through. I recommend marinating for 2-8 hours.
COOK CHICKEN: The instructions below are to grill the chicken. To see other methods of cooking chicken, read the portion of the post that is right above this recipe card. Lightly oil the grill grate or grill ridges on a grill pan or add 1 tablespoon oil to a skillet and then place the marinated chicken on the grill. Discard leftover marinade.
Grill for 10-12 minutes or until chicken juices run clear and internal temperature is at 165 degrees F. Flip the chicken halfway and brush it generously with the reserved 1/2 cup marinade.
MANGO SALSA: Take the remaining 1 tablespoon orange juice, remaining 1 teaspoon olive oil, 2 tablespoons lime juice, remaining lime zest, and remaining 1/4 cup cilantro and toss together.
(OPTIONAL: When grilling the chicken, also grill the mango. Brush with oil and grill on one side for about 4-5 minutes at medium-high heat.)
Chop the mango and avocado into bite-sized pieces. Add to the salsa along with the finely chopped red onion, red pepper, and jalapeño. Season the salsa to taste with pepper, salt, and remaining 1/4 teaspoon cumin and stir to mix.
ASSEMBLY: Serve grilled chicken over a bed of cilantro-lime rice or quinoa (if desired -- see recipe notes) and add spoonfuls of the salsa on top. Enjoy immediately!