1. Fry each of the ingredients separately in a pan/kadai after heating a tea spoon of oil.
2. Allow it to cool off. Grind them in a mixie.
3. Rasam powder is ready.

Note:
Powder should not be too soft. It shouldn't be ground too much.
Should be like shown in the picture.

Optional:
Ingredients can be added or removed.

Courtesy: http://tamilveg.blogspot.com/