For the chicken: Pat the chicken dry. With your hands, coat the chicken entirely with Sunny's 1-2-3 Spice Rub. Place in a plastic bag, press out the air, seal and refrigerate for at least 6 and up to 24 hours.
Remove the chicken from the bag, place in one layer on a baking sheet or tray and refrigerate, uncovered, for at least 2 hours and up to 6 hours.
Rest the chicken at room temperature for 2 hours. This is an important step, so you begin cooking the chicken when it is at room temperature. This allows the chicken to cook evenly throughout.
Preheat a grill or oven to 350 degrees F.
Place the chicken over the indirect heat of the grill and close the lid. If using the oven, put the chicken on a baking sheet lined with parchment or nonstick aluminum foil and place on the center oven rack. Cook for 30 minutes.
For the glaze: In a small bowl, whisk together the juice, honey and chili flakes if using.
Open the grill or remove the chicken from the oven and brush each piece liberally with the glaze. Quickly close the grill lid or return the chicken to the oven and cook until done and the chicken juices run clear, about 15 more minutes. Allow the chicken to rest, tented with aluminum foil, until the internal temperature registers 165 degrees F.
Sunny's 1-2-3 Spice Rub:
In a bowl, mix together the cumin, paprika, pepper, chili powder and salt. Store in an airtight container in a cool, dark place.