Combine the coriander, oregano, salt, pepper, cumin, cloves, allspice, and cinnamon. In a large bowl, whisk together 1/2 of the spice mix with the orange, grapefruit, and lime juices, and minced garlic. Add the chicken pieces and toss well to coat. Cover in plastic wrap, and refrigerate for at least 4 hours.

Heat a cast-iron skillet or grill over medium-high heat. Place the whole cloves of garlic and the chilies in the skillet. Cook, turning occasionally, until lightly charred on all sides, about 10 minutes for the garlic, and 25 minutes for the chilies. Transfer to a dish and set aside to cool.

Remove chicken from the marinade and reserve marinade. Working in batches, place in the hot skillet. Cook over medium-high heat for 8-10 minutes, turning once, until lightly charred on both sides. Transfer to a plate and set aside. 

Heat the canola oil in a large stock pot over medium heat. Add the onions and remaining spice mixture. Cook about 15 minutes, stirring occasionally, until soft. Add the chilies and garlic, and the chicken. Pour in the resrved marinade and the chicken stock. Bring to a boil, then cover and reduce heat to medium-low. Cook about 20 minutes, until the chicken is cooked through. Uncover and cook another 15 minutes, until the liquid has slightly reduced. Serve hot, with warm tortillas.