PRAWN PAPPAS - Kerala style shrimp curry

This recipe is quite famous in Kerala and is known for its spice. Not for the mild hearted folks :)
I dont know why its called 'pappas' though. I would love to know a reason.

Ingredients:

250 gm Shrimp (Prawns) remove shell and clean
2 Green chili
some Curry leaves

I
1/2 tsp red chili powder
3 tsp Corriander powder
1/4 tsp turmeric powder
1/4 tsp Pepper powder
2 Garlic flakes
1/4 tsp Methi (ulva)

II
Coconut oil
1/4 tsp mustard seeds
1 Onion, finely cut
1 tsp garlic flakes
1/2 tsp ginger, finely cut

III
1 ½ cup water
Tamarind (Imli/puli)
salt to taste

Method:
1) Heat ingredients listed in part I, then make a paste and keep aside.
2) Heat oil. Add ingredients in part II and fry
3) Add grinded masala to it and fry
4) Add water, tamarind and salt. Bring it to boil
5) On boiling, reduce gas to medium flame and add green chili, curry leaves and prawns. Cook till gravy is thick as desired.

Tip: Instead of tamarind, fry 3 cut tomatoes fand grind with masalas from part I
Replace 1/2 cup water with coconut milk to add extra flavor

Serves 4
Serving suggestion: with plain rice and buttermilk