Finely chop the green chillies, tomatoes and onions and store separately.
Wash the green lentils thoroughly and boil with turmeric in water rigorously for 10 mins followed by simmering on low-fire for 40 mins and it is done. Remove scum or froth, at intervals. (Alternatively you could pressure cook the lentils, which could be faster, though I haven’t tried it. Be careful that you do not over-cook and mash it up)
Heat oil in a non-stick pan, add the curry leaves and sauté for 30 seconds till it curls and gets fried.
Add the chopped onions and sauté till it is translucent, now add the chopped chillies and tomatoes, ginger-garlic paste and cook till oil separates from the mixture.
Add garam masala, chilli and coriander powder, salt and sauté for about 3-4 minutes till the raw taste disappears.
Add the cooked lentils and prawns and cook for not more than 10 minutes till all the masala and ingredients blend.