Split leg into thigh and drumstick portion nad remove the skin.
Brush tops of skinless legs with oil.
Mix spices, salt and sugar together in a small bowl, and rub spice mixture onto the pieces using your hands.
Place chicken in the refrigerator to "rest" for 1 hour.
Preheat barbecue and grill over medium heat, turning once, until fully cooked and browned - about 20 minutes or until a thermometer inserted into chicken reads 165°F.
Garnish with sprigs of thyme, if you wish.
NOTE: Traditionally this dish is eaten by shredding off pieces of chicken and wrapping in a tortilla. In that case, serve with salsa and warm tortillas.
In Canada, chili powder in a recipe usually means the store version that contains milder type red chilies that have been ground and flavoured with some cumin, oregano, garlic and/or salt. For a nicer taste experience buy some of the dried Mexican style chili powders. Ancho chili powder works well in this recipe but you can use chipotle or others.