Grate coconut, add chopped onion and the remaining ingredients. Hear one teaspoon oil, add the coconut and fry on a slow fire till it is golden brown. Remove and frind to a smooth paste. Wash and soak channa for about 10 to 12 hours. Cook i a pressure cooker for about 10 to 30 minutes. Heat oil. Add chopped onion and green chillies and saute. Add ginger and garlic paste and fry till it gives out an aroma. Add cooked channa, tomatoes, curry leaves and salt. Stir and cook for a few minutes. Add tamarind and water and cook for a few more minutes. Mix the ground coconut in a little water and add to the channa. Boil and remove from fire.