In a large pot or Dutch oven, heat the oil over medium-high. Add the garlic and onions and cook, stirring occasionally, until lightly golden in spots, about 5 minutes. Add the chicken bones and skin, cilantro stems, soy sauce and 8½ cups of water. Bring to a gentle simmer, and let cook until flavorful with a distinct chicken essence, 15 to 20 minutes. Using a spider or fine-mesh sieve, lift or strain out the vegetables and chicken pieces and discard.