Wash and soak the horse gram overnight. In the morning, boil horse gram with 2 cups of water for about 15 minutes till its boiled but not mushy.
After it cools, filter the legumes and keep the water aside.
Now start on the dry sabji. In a kadai, heat the oil. Add the hing and let it roast till 30 secs. Add the mustard seeds and let them splutter. Add the curry leaves and onions and fry till they are translucent.
Add the tomatoes and fry till they are mushy. This will take about 5-6 minutes.
Add the dry masalas and the drained horse gram. Let it cook for about 5-8 minutes till the masalas are well blended.
Now start the curry. Using a mixie make a paste of coconut, onion, tomatoes, curry leaves and both the chillies.
In a heavy bottom pan, heat oil and add the prepared paste. Roast it for about 6-8 minutes stirring constantly. When it starts to leave oil, add the water of horse gram that you have kept apart. Let it boil for about 5-6 minutes.
Serve hot with roti and rice.