Heat oil in a pan, pop mustard, cumin and fenugreek seeds. Then saute onion, garlic, green chili and curry leaves.
Add salt, turmeric and give a good mix. Then add tomatoes, mix, cover and cook until tomatoes are soft.
Add cilantro, roasted peanuts, sesame seeds, tamarind, stir well. Turn off the flame and let the mixture cool.
Transfer to a mixie/blender jar and grind to a fine paste. Add water as needed.