Heat a pan. Add dal, three cups of water, salt, turmeric powder and half the ginger. Bring it to a boil on high heat, then reduce heat and cook till just done.
In another pan, heat oil. Add asafoetida, cumin seeds, chopped onion and sauté till onion turns a light pink. Add the remaining ginger, chopped green chillies, chopped tomatoes and sauté.
Add red chilli powder and sauté till the oil surfaces Strain the dal and add to the masala.
Mix, add salt, garam masala powder, chopped coriander leaves and lemon juice. Cook for two more minutes.