1. Pour the lime juice on the chicken and let stand while you prepare the rest of the soup.
2. In a medium saucepan, place the coconut milk, lemon grass, grated lime peel, galangal or ginger, and chillis.
3. Bring the coconut milk to a simmer.
4. When the soup is simmering, add the lime-soaked chicken pieces and stir to distribute them.
5. Reduce the heat so the soup stays just below a boil and cook for 12 to 15 minutes or till the chicken pieces are finished cooking.
6. Remove from heat and serve immediately with fresh cilantro leaves for garnish.