Small onions - 1 cup
Tamarind - half the size of a lemon
Dry red chillies - 3
Curry leaves - a sprig
Gingelly oil - 1/2 ladle
Mustard seeds - 1/2 tsp.
Peel onions and grind it alongwith tamarind, curry leaves and chillies to a smooth paste.
In a heavy-bottomed pan, heat gingelly oil and add mustard seeds and hing. When mustard seeds splutter, add the ground paste, and salt. Stir it often so that it doesn't stick to the pan. When oil leaves the sides and the paste is thick, transfer it to a sterile bottle. Chilli powder can be substituted instead of red chillies.