Remove the skin of the ash gourd , deseed them and cut into small cubes.
Cook the ashgourd with little turmeric either in a cooker / microwave or directly in the vessel.But don't overcook and make it mushy. It should be about 75 % cooked.
Meanwhile grind the ingredients mentioned under " To grind " to a very very smooth paste adding little water.
Add masala paste and salt to the cooked veggie. Add buttermilk and mix such that the masala and buttermilk blends well
Add water to get the desired consistency. Let the mixture come to a boil. You will see that as it boils, majjige huli will thicken. Stir for 1-2 mins and switch off.
Heat oil in a small pan . Temper with mustard seeds ,hing & curry leaves.When the mustard crackles,pour the tempering over the curry.Ash gourd majjige huli is ready to serve.
Enjoy it with steamed rice along with some sun dried chillies / spicy pappad / spicy chutney .