Wash the tindora well in a bowl of water. I usually soak them in water for 10 minutes. Wash and drain them completely. You can either cut into thin roundels or vertically into thin strips.
I personally prefer roundels and have observed they cook faster when cut into roundels. Again it is a personal preference and observation, might not be the same for all.
Heat a wide bottom pan with oil, when hot splutter mustard seeds, add hing and curry leaves. To this now add chopped tomatoes, and turmeric powder. Let the tomatoes cook until soft and mushy.
To the mushy tomatoes, add chopped tindora, add sambar powder or red chili and coriander powder, salt and mix well.
Sprinkle water 2-3 times, cover and cook in a medium flame for 10-12 minutes. Open and stir in between twice. Check if the bottom is burning, if so then sprinkle little water and continue to cook with cover.
After 10-12 minutes, the tindora must have turned soft. Check doneness by pressing one in between your fingers, if still hard, let it cook covered for 2-3 more minutes.
To the cooked tindora add coconut. Mix well. Let this continue to cook without cover for another 8-10 minutes, for the bottom to turn a bit brown and golden.
Keep the flame medium or even low. Stir once or twice in between. If you feel it is burning in the bottom, sprinkle very little water and mix well.
After the said time, the tindora would have nicely crisped up in the bottom. Mix it well. I personally prefer few crispy tindora and few soft. Creates wonderful texture when you eat the vegetable.
Take it off the stove, serve it warm with rice. This delicious tindora fry can be packed for lunch too.