Grind together mustard seeds, cashew, coconut, garlic, ginger and green chilies. Keep aside.
Heat 1 tbsp. oil and fry the parwals till light brown. Keep aside.
Heat 2 tbsp. oil and temper with bay leaves, dry red chilies and panch phoron. Allow it to splutter.
Add the onion and fry till light brown. Add the fried parwals, ground paste, salt and turmeric powder. Mix well and add 1-2 cups water.
Bring it to a boil and simmer, covered, till the veggies are soft and the gravy turns slightly thick.