Wash toor dal and cook in water until it is very soft. This takes about 35–45 minutes, or until it becomes mushy. You can soak it ahead of time to cut down cooking time. Set aside.
Crush tomatoes and add water to bring to approximately 500 ml (per half tin of tomatoes).
Heat oil in the pan and sauté vegetables just to intensify the flavours. You can omit this step if you do not have time.
Add tomatoes, sambar powder and salt to the vegetables and cook until the vegetables are cooked through.
Mash the cooked toor dal and bring the sambar to the boil.
Cook for another 5 minutes. (Caution: do not cook over high heat since the mixture will burn easily.) Remove from the heat.
Heat oil in a frying pan and add mustard seeds. Fry until they pop, then add asafoetida.
Add this to the sambar.
Garnish with chopped coriander leaves and/or curry leaves.
Serve over rice or quinoa with ghee and pappadums.
Notes
If you have curry leaves you can add them with the coriander leaves.You can add sautéed onion with radish.You can also vary the recipe with different vegetables like aubergine, okra, etc.Sambar freezes well.If you have time, you can sauté the vegetables before adding the liquid.You can adjust the consistency of sambar by adding extra water to the dal, or add boiling water after finishing cooking.