Place coconut flakes onto a baking sheet and toast in the preheated oven until light brown, about 5 minutes.
Place coriander seeds in a skillet over medium heat. Roast the seeds, stirring constantly, until the they turn a light brown, 3 to 5 minutes. Remove from heat and grind in a blender until the seeds become a coarse powder.
Place coconut, ginger, fish sauce, soy sauce, sumac, garlic, chili powder, and lime zest in the blender with coriander seeds; pulse until the mixture is blended into a paste.
Place chicken in a roasting pan. Cut small slits near the chicken breasts, thighs, and wings with a sharp knife. Pack 1/3 of the paste into the slits, under the skin of the chicken.
Dust chicken with salt; rub 2/3 remaining paste on chicken skin until thoroughly covered. Lay chicken breast-down in the pan.
Refrigerate for 8 hours to overnight.
Preheat oven to 350 degrees F (175 degrees C).
Bake chicken in the preheated oven until golden brown and no longer pink in the center, about 2 hours. An instant-read thermometer inserted into the thickest part of the thigh, near the bone should read 165 degrees F (74 degrees C).