Grind together red chillies, ginger and garlic. Mix the paste with red chilli powder, lemon juice, turmeric powder and salt and marinate the chicken pieces in this for three hours.
Heat two tablespoons oil in a thick bottom pan and sauté the marinated chicken pieces on high heat till they are dry and slightly brown. Drain and set aside. Add the remaining oil to the pan and sauté the onions till brown. Add curry leaves and stir well. Add tomatoes, salt and coriander powder and cook till oil leaves the masala.
Add the chicken pieces and one cup of water. Cover and cook till the chicken is done and the masala coats the pieces. Add tamarind pulp dissolved in half a cup of water and simmer for ten minutes, stirring occasionally. Add garam masala powder and mix lightly. Adjust the seasoning and add crushed peppercorns.
Garnish with coriander leaves and serve hot.