Roast cashew nuts, poppy seeds, coriander seeds, coconut, red chilies and cumin seeds and garlic on a non-stick pan on a low flame till you get an aroma, grind to a fine paste with vinegar and little water.
Heat oil in a heavy bottom vessel and fry finely chopped onions on a low flame till the onions are golden in color.
Add the kept aside ground paste and saute on a low flame till oil separates.
Add tomatoes puree and cook.
Add prawns and mix well.
Saute for 5-7 minutes on a low flame.
Add water, salt to taste and sugar.
Bring to a boil.
After a boil, simmer.
Cook till prawns are done.
Garnish with lemon juice and finely chopped coriander leaves.