Add 1 tsp of oil and saute Onion, mustard seeds, fenugreek, red Chilli and salt till onions turns translucent. Cool and grind the mixture into a paste without adding water
In a heavy bottomed pan add oil, once when the oil becomes hot add mustard seeds and asafoetida; let it crackle. Add the ground onion paste, tamarind extract and turmeric powder and cook in low flame
Cook till the onion paste reaches a thokku consistency and oil is separated. Stir occasionally. If it is dry add little oil in between.
Switch off the flame and allow this to cool