Indian
Pressure-cook the toor dal with 450 ml of the water and the turmeric for 4 whistles (or simmer covered for 40 minutes) until very soft, then mash it smooth.
Soak the tamarind in 200 ml of warm water from the measured amount for 10 minutes, squeeze it out and strain the liquid; discard the pulp fibers.
Put the vegetables, onion and tomatoes in a large pot with the remaining 350 ml water and a little salt and simmer for 10 minutes until the vegetables are almost tender.
Add the tamarind water and sambar powder and simmer for 5 minutes, until the raw tamarind smell is gone.
Stir in the mashed dal and the rest of the salt and simmer for 5 to 8 minutes; add a little water if it is thicker than a pourable stew.
Heat the oil in a small pan, add the mustard seeds and, when they pop, the red chilies, curry leaves and asafoetida; fry for 20 seconds and pour over the sambar.
Sprinkle with cilantro and serve hot with rice, idli or dosa.