If you are grilling, coat the grill rack with cooking spray and heat the grill for direct heat cooking. If you are roasting, preheat the oven to 425F and coat a large baking sheet pan with cooking spray.
Combine the sugar, cumin, salt, garlic powder, ginger, cinnamon, cayenne and black pepper in a bowl, working the mixture with your fingertips to get rid of any lumps.
Shape and trim the thighs. Pat the mixture over the entire surface of the thighs.
To roast: place in the oven, skin side up, and cook until the largest thigh reaches an internal temperature of 170-175F, about 30-35 minutes depending on the size of the thighs. To grill: place on the grill skin side facing down and cook 15 minutes. Turn and cook until the largest thigh reaches an internal temperature of 170-175, about another 15 minutes.