Combine the seeds, mango, turmeric and chilli powder in a pressure cooker. Add very little water along with salt, just to cover the base and pressure cook on high flame for 5-6 whistles. Switch off and allow it to cool completely.

Grind all the ingredients in the "for grinding" section to a smooth paste.

Open the cooker and switch on the flame. Add the ground mixture and additional water if required. Heat the mixture - do not boil otherwise. Switch off.

Heat oil in a small sauce pan, splutter the mustard seeds and briefly fry the curry leaves. Add into curry, serve hot with rice.