Pre-heat oven to the highest temperature available (mine was 250°C centigrade).
Apply 2 tsp oil all over the aubergine and place it in the oven for 40 minutes or until it is cooked inside. The peel of the aubergine would look wrinkled and black.
Remove from the oven and let it cool.
Peel the skin off and the inside should be soft.
Chop the cooked aubergine then grind together with the green chillies, salt & tamarind and add the chopped raw onion to it.
Heat 1 tsp oil in a pan and add mustard seeds, red chilli and curry leaves and let them splutter.
Add the above seasoning to the aubergine mixture.