Wash arhar dal and moong dal with water and soak with 2 cups of water for 1 hour.
Heat the ghee or oil in a pressure cooker on medium flame.
Add cumin seeds and asafoetida (hing), when they start splutter.
Add chopped onion and saute for 5 minutes till to color change.
Add garlic ginger paste and saute for 2 minutes.
Add chopped green chilies and tomatoes and cook for 2 minutes.
Add coriander powder, turmeric powder, salt, red chili powder and cook for 3-4 minutes.
Add dal with 2 cups of water and cover the pressure cooker with lid.
Cook for 2 whistles and remove the cooker from flame and keep aside.
Open the lid once the pressure release.
Add desi ghee in tempering pan. Add cumin seeds, red chili powder, whole red chilies and when they start splutter.
Pour the tadka over the dal, add garam masala, lemon juice and chopped coriander leaves and mix well.
Now Punjabi Dal tadka is ready to serve with roti or rice.