Wash and soak Chana Dal in enough water for at least 15-20 minutes. Dal becomes soft as it absorbs water. This cuts on the cooking time.
Wash and peel Lauki(Bottle Gourd) and cut into cubes.
Discard water from Dal, take fresh water in a pressure cooker, add dal and lauki pieces and put on medium flame.
When the water starts boiling, remove the froth is formed and floats on the top.
Add turmeric powder and salt mix, put the lid on and cook on medium flame till 3-4 whistles. You can cook this dal in a saucepan also but it will take too long to cook. So if you are planning to cook it in a saucepan, soak the dal overnight or at least 5-6 hrs.
After 3-4 whistles, lower the flame and cook for another, 10 minutes.
Adjust the consistency of the dal by adding water. We like thick dal when having it with chapatis and a little thinner consistency when having with rice
Meanwhile when the Dal is cooking in pressure cooker, finely chop onion, tomatoes and crush or very finely chop ginger and garlic.
In a pan, add ghee or oil. I make the tempering for dals(lentils) in desi ghee(Indian Clarified Butter). You can use any flavorless oil.
When the ghee heats, add cumin seeds, when seeds start spluttering, add finely chopped/ crushed ginger and garlic and saute for a minute.
You can also add finely chopped 1-2 green chillies depending on your spice level. Many people add curry leaves in the tempering, I don't add in this dal, love the flavor of curry leaves in Arhar/Toor Dal (Pigeon Pea lentil curry) .
Add onion(if you are using it), saute till it turns light pink, add tomatoes and cook till the tomatoes get mushy and soft.
Add garam masala, and cook for another minute and then mix tempering in the dal.
Mix nicely and let it cook for another 5-6 minutes so that the flavors of masala, infuse with dal.
Garnish with finely chopped fresh Coriander leaves.
If you want just before serving make the tempering of cumin seeds and red chilli powder in a ½ Tsp of ghee/oil and add to dal. It will enhance the flavor and aroma of dal. Skip this step if you want low fat and less spicy dal/curry.