For the caramel sauce, heat the sugar in a pan over low heat, stirring continuously, for three to five minutes or until it begins to melt and caramelise.
Remove from heat and add the fish sauce. Mix and return the pan to the heat. Bring the mixture to a boil over a medium heat. Reduce heat and simmer uncovered for three to five minutes, stirring continuously till the mixture turns to syrup. Add the leek and cook for one minute. Add the shallots, crushed peppercorns and mix well. Remove from heat. Add the chicken wings and ginger and bring the mixture to a boil over high heat. Reduce heat, cover and simmer for about thirty minutes, stirring occasionally, until the chicken is cooked.