1Slit the chillies lengthwise, scrape out the seeds if you want it milder, and fry them in 2 tbsp oil until blistered. Lift out.
2Dry roast the peanuts, sesame, coconut, coriander seeds and half the cumin, each separately, on low heat.
3Fry the onion in 1 tbsp oil until golden. Grind with the roasted mix, ginger garlic paste, chilli powder, turmeric and a little water to a smooth paste.
4Heat the remaining oil. Add mustard, the rest of the cumin, nigella, fenugreek and curry leaves, then the paste. Fry on low, stirring.
5Add tamarind extract, water, salt and jaggery. Simmer, then add the chillies and cook on low until the gravy thickens.
6Rest for 15 minutes before serving with biryani.
Serve it like this
Serve hot in a deep bowl with a swirl of ghee or a few coriander leaves on top, and rice or rotis on the side.