Dry roast the chana dal, urad dal, coriander seeds, dry red chilies, dry grated coconut separately until toasted and smell fragrant. Cool to room temperature before grinding.
Blend all the roasted ingredients along with tamarind and salt into a smooth powder.
Heat oil in a small saucepan, add the tempering ingredients and once the seeds start to splutter, turn off the heat and let the tempering cool for a few minutes.
Add the tempering to the ground powder, mix well and store in an airtight container.