1. In a stockpot, combine chicken, onion, carrots, celery, parsley, whole garlic, bay leaf, salt, peppercorns and water. Bring to a boil over high heat. Using a slotted spoon, skim off foam. Reduce heat to medium-low and simmer, uncovered, until chicken is falling off the bone, about 1½ hours. Drain, reserving chicken and liquid separately. Let cool. Cut the chicken into bite-size pieces, discarding skin and bones. Skim off fat from the stock.
2. Measure 2 cups (500 mL) of chicken and set aside in the refrigerator. (Refrigerate remainder for other uses, see Notes.) In a large saucepan or stockpot, heat oil over medium heat for 30 seconds. Add leeks and cook, stirring, until softened, about 5 minutes. Add minced garlic and ginger and cook, stirring, for 1 minute. Add rice and toss to coat. Add reserved stock and bring to a boil. Reduce heat and simmer, uncovered, until rice is quite tender, about 1 hour. Add reserved chicken. Cover and simmer until chicken is heated through, about 15 minutes.
Variation: Substitute an equal quantity of rinsed wild rice for the mixture. You may need to increase the cooking time, depending upon the size of the grains.