Sift the flour with the baking powder into a bowl.
Add the nigella seeds, salt, and the melted butter or ghee and crumble into small lumps.
Add the water a little at a time to make a firm but pliable dough. Alternatively, you can make the dough in a food processor.
Cover the dough and set aside for 30 minutes.
Divide the dough into four pieces (this makes it more manageable).
Roll out to just under 1/4 inch (5 millimeters) thick. Using a knife, cut the dough into strips about 1 1/2 inch (4 centimeters) long and 1/2 inch (1 centimeter) wide. You could also cut them into similar-sized diamond shapes, but they should all be the same size and shape so they cook at the same rate.
Meanwhile, heat a 2 1/2 inch (6 centimeters) depth of oil in a karai or wok over high heat.
Reduce the heat to low and fry the Nimki in small batches until golden brown.
As the Nimki are done, remove them using a slotted spoon and spread out on a non-metallic plate to cool completely and become crisp, before transferring to an airtight container, where they should keep for up to 2 weeks.