Pound ginger, garlic and salt together in a mortar and pestle then marinate chicken pieces in this mixture and set aside for 1 hour.
Grind chillies, shallots, ginger and candlenuts until fine.
Mix the tamarind paste with the water then strain the juice.
Put the blended spices in a saucepan then add the coconut milk and tamarind juice. Cook slowly on low heat stirring frequently until it comes to a boil. Add salt and sugar to taste and cook until the sauce thickens.
Dip the chicken pieces in the thick coconut sauce and place over hot charcoal barbecue. Baste the chicken frequently with the sauce on both sides and continue cooking until the chicken is evenly browned and cooked through.