1. To make rasam powder, dry roast 20-25 black peppercorns, 1 tbsp coriander seeds, 1 tsp cumin seeds, a pinch of fenugreek seeds and 1 tbsp pigeon peas till fragrant in a non-stick pan. allow to cool and transfer into a blender jar and blend to a fine powder.
2. Heat a non-stick deep pan, add boiled split pigeon peas (toor) dal and the water in which it was cooked and mix well.
3. Add 1 chopped tomato, salt to taste, ¼ tsp turmeric powder, 1 tbsp tamarind pulp, ½ tsp red chilli powder and 3 tbsps ground rasam powder and mix well. add 3 cups water and cook till the mixture reduces to half. take the pan off the heat.
4. To make the tempering, heat 2 tbsps oil in a small non-stick pan. add ½ tsp mustard seeds and let them splutter. add ¼ tsp asafoetida, 2 dried red chillies, 8-10 curry leaves and 2 tsps black pepper powder. pour this tempering over the rasam and cover the pan to trap the flavours.
5. Add chopped coriander and pour the rasam into a serving bowl. serve hot with steamed rice.