Put all your ingredients—black peppercorns, cardamom pods, cumin, fenugreek, coriander, and mustard seeds in the frying pan and heat them mildly.
Heat the frying pan until the ingredients are dry roasted. It is best to roast all the ingredients together, however, you can also dry roast them individually if time is not an issue.
In order to avoid burning the ingredients and spices, keep stirring the base, mixing the dish well. You will notice that the mixture has now taken a new form; fenugreek turns a golden brown and mustard seeds start to pop.
Now use a spice grinder to grind the dry roasted spices. There are several ways to do this, but the most hassle-free way to grind the dry roasted spices is to use electric coffee grinder. Make sure you do not get the flavour of your curry powder mixed with coffee, as it usually happens when you use electric coffee grinders.
Put chili, ginger, turmeric, garlic and onion in a bowl and mix them along with spices. Make sure that you use a larger bowl to blend the curry powder well. Small bowls will make it hard to mix the material easily and it will not be blended to take the right form.
Once you have the powder ready in the bowl as the material typically takes a new form (powder-like), you can pour it in to a glass jar. Glass jar is used to preserve the powder for a longer period and the spices also remain fresh.
After you have put the powder in the glass jar, seal it tightly so it remains air-tight for weeks. Now, keep the sealed glass in a dry but cool place for at least five to six months.