Snap off the stems of the chilies and discard the seeds. With kitchen scissors cut the chilies into 1 inch pieces and place in a medium saucepan. Add 1/2 cup water to the saucepan along with garlic, cumin, oregano, cinnamon and a pinch of ground cloves. Bring to a boil. Reduce heat, cover and let simmer for 15-20 minutes. Pour the mixture into a blender and process until smooth. If you end up with less than 1/2 cup then add more water until you have that amount. Season to taste with salt. Let cool for at least 20 minutes before proceeding.
Place the chicken pieces in a large zip-lock bag and pour the chile mixture over the top. Add the vegetable oil. Seal the bag and marinate in the refrigerator, turning occasionally, for at least 4 hours or overnight.
Prepare the grill. Grill over medium flame for 10 minutes, turn and grill for 10 minutes more. Turn again and grill for a final 10 minutes. When done, transfer to a platter and tent with foil. Let rest for at least 5 minutes before serving.