Place toor dhal in a saucepan with 500ml water and bring to the boil. Reduce heat to medium-low, and cook until soft, about 15 minutes.
In another saucepan, mix together the tamarind pulp then stir in 100ml water to make a watery juice. Bring to a boil over medium-high heat. Add the green capsicum and tomato to the tamarind juice then continue to boil until the vegetables are soft and the liquid has reduced to almost half.
Meanwhile, grind the coriander seeds, channa dhal, coconut and chillies to a paste using a mortar and pestle or food processor. Add this paste to the tamarind sauce, then stir in the toor dhal until everything is well blended. Bring to the boil once again, then remove from the heat and set aside.
Heat oil in a small frying pan over medium heat Add the mustard seed, cumin seed and asafoetida. Once the mustard seeds start to pop and the mixture is fragrant, remove from heat and stir into sambar. Serve hot.
Toor dhal, the most widely used dhal in India, will be available in Indian or health food shops. You could, however, substitute yellow split peas in a pinch. Channa dhal are split chickpeas without their skins, at Indian or heath food shops.
Better pre-soak the peas. They'll never get soft in just 15 minutes cooking (w/o pressure). Seasoning is a good combination. - 29 Sep 2008
Altered ingredient amounts.
I suggest adding 4 large tomatoes instead of 1 and halving the tamarind. If you don't mind the extra calories, a cup of coconut milk adds a delicious richness (don't use regular milk!). If using potatoes, prick them raw, dice into bite size pieces and cook them in the tamarind (or tomato) juice. Okra is GREAT in this recipe. - 29 Sep 2008