1. Shell, devein, wash and pat dry prawns.
2. Blend the peppercorns, cardamoms, cinnamon, cloves, cumin and red chillies with the vinegar in a blender.
3. Keep aside. Heat oil in a kadhai and deep fry prawns to a golden brown.
4. Remove. Add the onions to the hot oil.
5. Saute till golden brown.
6. Add the ginger and garlic pastes and stir for a minute.
7. Add the tomatoes and the blended paste.
8. Stir for 2-3 minutes.
9. Add the fried prawns, curry leaves and sugar and cook till prawns are tender.
10. Serve hot with steamed rice or any Indian bread.