Wash and Peel the squash, cut into equal cubes. Keep aside.
Grate coconut and keep aside.
Soak the tamarind in 4- 5 TBSP hot water for 15 minutes.
In a pan, heat half the oil, splutter the mustard seeds, urad dal and half the curry leaves.
When the dal turns brown, add the cubed veggies and saute for 1- 2 min
Add salt and 1/4 cup hot water and let it cook till 80% cooked (takes about 5-7 mins depending on quantity and the squash variety)
Meanwhile, make a paste of all the ingredients under the "To grind" list. Add 2-3 tsp of water to grind smooth.
Once the veggies are cooked, add this ground paste to the pan, and add 1/2 cup hot water.
Mix well and let the veggies simmer for 5-6 mins.
Prepare a slurry with the rice flour and 3 tsp of water.
Add this rice slurry to the pan. The curry will thicken in 1-2 mins.
At this point, make a second tempering with the remainign oil, cumin, curry leaves
Add this tempering to the curry. Serve hot with rice / chapati (Indian unleavened flatbread)