Put the soup chicken in a saucepan, add garlic, ginger and soy sauce. Top up carefully with cola. Simmer the chicken over medium heat for 35 minutes. In the meantime, cut the leek into rings, add after the 35 minutes and simmer for 20 minutes or until the chicken is tender.
Take the chicken out of the pot and loosen the meat from the bones. Remove the skin and chop the meat into bite-sized pieces. Season the sauce to taste and thicken with starch. Add the meat again and bring to the boil again.
Rice goes best with it. If you like it spicier, you can make a salsa with fresh chili peppers, a little oil, vinegar and salt.