Thakkali Thairu Chaaru / Tomato Yogurt Curry

Ingredients :-
1.Tomato - 2 meduim size or 1 big ( sliced or cut into cubes)
2.Yogurt / Curd - 1 cup
3.Ginger - 1tbspn (chopped or mashed)
4.Green Chillies - 2-4 (slit open)
5.Turmeric Powder - 1/2 tspn
6.Cumin Powder - 1tspn or to taste 
7.Salt - to taste
8.Oil - 1tbspn or as required
9.Shallot (kochulli) - 1 (sliced)
10.Curryleaves - 1 string
11.Mustard seeds - 1tspn

Preperation :-

1.Take a curry chatti or a kadai/deep pan and pour in 2 cups of plain water.
2.Add tomato with ginger, greenchillies, salt and turmeric powder to it.
3.Cook it well that tomatoes are soft enough to mash a little with a spoon.
4.Mash it and cook it with open lid. Let the excess water get evaporated and it is little thick. 
5.Meanwhile, pour yogurt/curn in a blender with a little turmeric powder, cumin/jeera powder, salt and blend it well.
6.Now, mix this blended yogurt into boiling tomato mix and stir it with a spoon till the curry is hot.
7.Switch off the stove or it will start boiling. Not good for yogurt.
8.Take another pan and heat oil. Splutter mustard seeds.
9.Add sliced shallot to this and fry it well with a pinch of salt till shallots are brown in colour. Not burned but kind of burned.
10.Add curry leaves and a pinch of redchilli powder or whole red chillies and fry it for few seconds in low flame.
11.Switch off the stove and add this tadka to tomato yogurt mix.