Clean and wash the mussels. Apply salt and lemon juice. Keep it aside. Slice one onion and chop the other. Soak the tamarind in the warm water. Squeeze to remove pulp.
Dry roast cloves, black peppercorns, cinnamon, caraway seeds, coriander seeds, red chillies and grated dry coconut separately. Mix with browned onions. Cool and grind to a fine paste adding a little water. Grind scraped coconut in a mixer and extract coconut milk.
Heat one tablespoon oil in a pan and fry the sliced onion till golden brown. Heat the remaining oil in a deep pan, add chopped onion and sauté till light golden brown. Add ginger paste, garlic paste and sauté for half a minute.
Add ground masala and sauté on low heat for two to three minutes. Add one cup water and bring the mixture to a boil. Add mussels, salt, turmeric powder and coconut milk. Check the seasoning and cook for five minutes.
Garnish with coriander leaves and serve hot, preferably with steamed rice. Serve hot preferably with steamed rice.