In a hot pan kept over low heat, add the coriander seeds and fry them till they are aromatic (approximately 30-60 seconds), stirring constantly. Remove the seeds and set them aside on a plate to cool.
Add cumin seeds to the pan, fry them for 10 seconds or so before taking them out of the pan & adding it to the plate to cool.
Next roast the fenugreek seeds very lightly – take it out of the pan & add it to the plate to cool
Lastly, add the mustard seeds and peppercorns. Roast for about 30 seconds before adding the curry leaves. Stir constantly till the curry leaves are dry.
Add the turmeric & asafoetida, give it a quick stir
Turn the stove off
Transfer spices from pan onto a plate & let it cool down for 3-5 minutes before grinding them to a fine powder in a spice grinder
If the mixture is warm after being ground, transfer it to a plate and once it cools down, transfer the powder to an air-tight container and store it in a cool place. Stores well for 3-6 months.
While making sambar, add 1 tsp per person to the sambar mix if you want it mild. Add around 2-3 tsps per person if you want it more spicy