Marinade the chicken with the ingredients listed under that section. and keep for a minimum of 30 minutes or more.
While the chicken in marinading, dry roast and grind the ingredients listed under that section with a little bit of water and make a wet paste.
In a heavy bottomed pan, heat the oil and lightly sweat the onions.
When the onions are golden brown, add the chicken and the wet paste.
Add a tbsp of tamarind paste and the sugar. The sugar is just my addition to balance the tanginess from the vinegar as well as the tamarind.
Now stir and mix everything properly until all the spices start releasing oil. COntrol the temperature as you do this.
Adjust the seasoning and then transfer everything to a pressure cooker.
Add half a cup of water to the pan and swirl it around to gather all the spices which are stuck to the bottom and then transfer to the pressure cooker.
Add 2 cups of water and close teh lid of the pressure cooker.
Cook for 15 -20 minutes. When the steam releases, open the lid and check the seasoning.
Serve it with some steamed rice.