1. Wash the dal and set aside.
2. Heat oil in a pressure cooker and fry the onions to pink, followed by the cumin, mustard, garlic, asafoetida, chillies and turmeric.
3. Fry for a minute before adding the daal.
4. Fry well for 1-2 minutes and then add the tomatoes, salt and 1.5 cups water (enough to cover the daal in the cooker).
5. Close the cooker and cook on high for 1 whistle.
6. Turn off & wait till all the steam is out.
7. Open and stir; add water to get desired consistency.
8. Garnish with coriander and serve hot with rice or roti.

Variation: Add the juice of 1 small lime or 2 tbsp tamarind paste for extra zing!