Soak the mustard seeds and cumin seeds in water for 20 - 30 minutes. Remove from water and transfer to a grinder. Also add red chillies, half of the crushed garlic and tomatoes to the grinder. Grind them together to a fine paste. Add little water else the seeds will not turn fine paste.
In a pan heat oil and add cumin seeds and let it crackle. Then add a pinch hing, rest crushed garlic, green chillies and saute. Then add onion and saute till onion is translucent.
Add the spices ( Coriander powder, turmeric powder, red chilli powder). Saute for 10 seconds and then add chopped vegetables and mix well.
Add salt and saute for 2 minutes.
Add 1/2 glass water and cover with a lid. Let it simmer and boil the vegetables till they are cooked. It will take 7 - 10 minutes
Then open the lid and check with a spoon if vegetables are cooked. Add the mustard and tomato paste to the curry and mix well.Let it simmer for 3 - 4 minutes.
Turn off the gas and add 1 tsp dry mango powder and stir well.
Garnish with coriander leaves and serve hot.
Soak mustard seeds for 20 - 30 minutes before grinding to fine paste.Add tamarind paste with the mustard seeds and grind them together.