Place the chile, onion, scallion, 1 teaspoon fresh thyme, salt, peppercorns, allspice, ginger, nutmeg, white wine vinegar and soy sauce in a blender. Secure the lid and blend on high until the spices are ground and the mixture is smooth. Puree the sauce ingredients in a blender to a smooth paste. Scrape out into a gallon zip-top bag or a storage container large enough to hold the chicken breasts.
Cut 4 slashes in each chicken breast, across the grain, so the marinade can penetrate into the meat. Marinate the chicken in the jerk sauce overnight. Take out and drain any extra sauce off, then lightly coat with olive oil. If you can, use wood chips to smoke the chicken on the grill. Grill over indirect heat to slow cook, or bake in a 400 degree oven for 20-25 minutes, or until the chicken registers 160 F when you insert an instant-read thermometer in the fattest part of a breast.
In a measuring cup, combine the water and coconut milk, reserve. In a 2 quart pot, place the coconut oil and put the pot over medium-high heat. Let the oil heat for a few seconds, then add the carrot, bell pepper, the whites of the scallions, and the reserved 2 teaspoons fresh thyme. Stir until the vegetables starts to sizzle, then lower the heat and cook for 10 minutes on low. Add the coconut milk mixture and bring to a full boil. Quickly stir in fonio, cover, take off the heat and let stand for 5 minutes. Uncover and fluff the fonio with a fork.
Chop the mango and toss with the fresh lime juice just before serving.
Serve about 3/4 cup fonio with each chicken breast and spoon chopped mango over the chicken.