1. Hack the chicken into small serving pieces, chopping through the bones with a sharp cleaver. Remove the outer leaves of the lemongrass and finely slice the tender white part at the base of the stalks.
2. Bruise with a mortar and pestle or the handle of a cleaver. Finely slice the scallions, including the green tops. Mix the chicken with the salt, ¼ teaspoon pepper, the lemongrass, and scallions and set aside for 30 minutes.
3. Heat a wok, add the oil, and when oil is hot add the chicken mixture and stir-fry for 3 minutes. Add chili peppers, and stir-fry on medium heat for 10 more minutes or until chicken no longer looks pink.
4. Season with sugar and pepper and add the Chicken Stock. Chow or stir for a few minutes. Garnish with the peanuts, nuoc mam, and coriander. Serve with rice, if desired.
