Place the dal in a large saucepan and stir over medium heat until dry. Add the oil, chiles de arbol, garam masala, feugreek & asafoetida and cook stirring until the dal is golden, about 3 minutes Reduce heat if too much smoke arises. Add ginger, garlic, serrano peppe, coriander & paprika and stir for another 5 minutes.
Add water and salt and bring to a boil over high heat. Recuce heat to low, cover pan, and cook stirring occasionally, until the dal is soft & creamy, about 1 hr, adding more water if it dies too quickly. Mix in the tomatoes and cook until they are quite soft, about 5 minutes Transfer to a serving dish, mix in the cilantro and serve.