Whatever might be the rice or curry, rasam has to be there for all my family members at home. As per them, a meal is not complete without rasam. If you know me, I always prepare freshly ground rasam masala everytime when I prepare Rasam. That's one of the reason, I don't prepare and store rasam powder at home. but, power cuts have forced me to prepare and store it in a container for a week's use. My advise will be to prepare it in a smallar quantity to retain its freshness, aroma and flavor.
Also, note that I haven't added toor dal in my rasam powder. My mother-in-law usually adds toor dal in all rasam recipes whereas my mom adds only in Dal rasam(Paruppu Rasam) and I have adopted this procedure until now. So, if you want in include toor dal, add 3 tablespoons of toor dal to the below ingredients.
Preparation Time: <15 minutes
Makes: 1/2 cup approximately
Black Pepper corns - 1/4 cup
Cumin seeds - 2 tablespoons
Coriander seeds - 2 tablespooons
Dry red chillies - 5-6 nos
Asafoetida / Katti Perungayam - a very small piece
Curry leaves - 3 strings
1) Sun dry all the ingredients for an hour. You can also dry roast them in a heavy bottom pan without burning until all the ingredients start releasing nice aroma.
3) Store it in an air tight container and keep it inside the refrigerator. It stays good even at room temperature.
1) If you don't have katti perungayam at home, prepare rasam powder without it and add the asafoetida powder while preparing the rasam.
2) If you don't add fenugreek seeds while seasoning the rasam, add it (about 1/4 teaspoons to 1/2 teaspoons) to the above ingredients and make a powder of it.