In a bowl add tamarind and pour over 100 ml of boiling water. Set aside for a couple of minutes to soften.
Strain the tamarind liquid and press the pulp to extract as much liquid as possible.
Put the tamarind pulp back into the bowl and add another 100 ml of hot water. Mix and again, pass through the sieve to separate the liquid, and squeeze the pulp to extract more liquidRepeat this process two more times using 100 ml of water each time. Then discard the remaining seeds and pulp.
Add the tamarind liquid into a pan and bring to a rapid boil.
Add the sugar and reduce to the heat to a simmer and allow the tamarind liquid to reduce for about five minutes.
Add the dry ginger powder and kala namak and continue to simmer and reduced to a syrup consistency.
Remove from heat and set aside.
In a small pan heat the oil over a high heat. When the oil is hot, add the cumin seeds and the nigella seeds. Once theY crackle and change colour (usually no longer than thirty seconds), remove from heat and add to the tamarind syrup. Mix well.
Transfer into sterilised bottles. The chutney is ready for use.