In large saucepan place chicken breast with stock and bring to a boil. Skim and discard foam. Add 1 1/2 teaspoons salt, cracked peppercorns, oregano and garlic. Reduce to a simmer and cook 30 to 35 minutes, until the meat is tender. Lift out chicken and transfer to a platter. Cover with a damp towel and reserve. Add chicken livers to saucepan and simmer 6 - 8 minutes. Remove with a slotted spoon and transfer to the platter with the chicken. Strain the stock through a very fine strainer, discarding the solids, and skim off any fat from the top. Reserve. When the chicken is cool enough to handle, remove the skin and pull the meat from the bones. Shred chicken into strips, thinly slice the livers and reserve. In large stockpot heat the chicken fat or olive oil over a medium low heat. Add onions and cook with remaining 1 teaspoon salt and ground black pepper, until onions turn translucent, about 10 minutes. Add green peppers and cook for about another 5 minutes. Add tomatoes, chicken and livers, reserved stock, lime juice and grapefruit zest, or bitter lime juice. Bring to a boil then reduce to a simmer and cook until flavors meld, about 10 to 12 minutes. Remove grapefruit zest with a slotted spoon. Serve hot with garnishes scattered over the soup.