Soak mochai overnight. Take it in a cooker, add salt and water. Pressure cook for 6 whistle, simmer the flame and cook for 15 mins. Turn off the heat and let the steam go by itself. Set aside.
Heat oil in a pan. Add fennel seeds and let it sizzle. Add onions, garlic and tomatoes. Saute for 2 mins. Add coconut and stir fry for 3 to 4 mins. Take it off the heat and puree till smooth.
Heat oil in the same pan, Add in mustar, urad dal and curry leaves. Let them sizzle.
Add onions, garlic, tomatoes and cook till soft.
Add spice powders, salt and mix well.
Add in tamarind water, water, ground masala, salt and sugar. Bring it to a boil, simmer for 15 to 20 mins till oil floats on top.