In a heavy bottom pan at low heat, dry roast the dry red chilies, coriander seeds, onion seeds, fennel seeds, mustard seeds and cumin till slightly browned and fragrant. This should take about 4-5 minutes.
Let it cool slightly for 5-10 minutes.
Grind in the blender with rest of the ingredients to make a coarse powder.
Store in an airtight container. It lasts fine for up to a month in a cool and dry place or can be stored in a refrigerator it for about 2 months.