Rinse 1/2 cup green moong beans for a couple of times and then soak in enough water for an hour. You can also soak them for a couple of hours or overnight. If soaking overnight, then the pressure cooking time will reduce.
Chop 1 medium onion, 1 large tomato and 1 to 2 green chilies. Crush the ginger and garlic to a paste in the mortar-pestle.
Making Green Moong Dal
Heat 2 tbsp oil in a pressure cooker.
Add the whole spices – 1 medium tej patta/Indian bay leaf and 1/2 tsp cumin seeds. Saute till the cumin seeds splutter.
Then add the chopped onions. Saute the onions till light golden.
Add 1 tsp ginger-garlic paste and chopped green chilies. Stir and saute till the raw aroma of ginger-garlic goes away.
Now add the chopped tomatoes and 1/4 tsp turmeric powder, 1/4 tsp red chili powder, 1/2 tsp coriander powder and 1/4 tsp garam masala powder.
Stir and saute till the tomatoes soften, become pulpy and you see oil releasing from the sides.
Drain and add the moong beans. Stir very well.
Add 2.5 to 3 cups water and salt as per taste. Stir very well.
Cover and pressure cook sabut moong dal for 10 to 12 whistles or 15 to 17 minutes on a medium to high flame till the moong beans are softened thoroughly.
When the pressure settles down on its own, open the lid and check the moong beans. If they still have slight bite to them, then add some water and pressure cook for some more whistles.
If the mixture looks dry, then you can add more water. Keep the cooker on the stove top and simmer the moong dal for 5 to 6 minutes, stirring at intervals.
The consistency of the dal should not be watery. While cooking you can mash a few lentils with the back of the spoon.
Tempering For Green Moong Dal (Optional)
Heat 1 tbsp oil in a small pan or tadka pan. Splutter 1/2 tsp cumin seeds first.
Switch off the flame and then add a pinch of asafoetida and 1/4 tsp red chili powder. Stir.
Add this tempering to the dal. Stir well.
Add 3 tbsp chopped coriander leaves. Stir again.
Serve green moong dal with steamed rice or chapatis.
While serving this green gram curry, you can garnish with a few coriander leaves if you want.