Clean and wash the clams. Apply salt and lemon juice. Keep aside for fifteen minutes. For the masala, sauté the onions in one tablespoon of oil till golden brown.
Dry roast the cloves, peppercorns, cinnamon, caraway seeds, coriander seeds, red chillies and dry coconut separately. Mix with browned onions and grind to a very fine paste, adding one-fourth cup of water.
Add half a cup of warm water to the scraped coconut. Grind and squeeze out thick milk. Keep it aside. Heat three tablespoons of oil in a deep non stick pan.
Add the onions and sauté till light golden brown. Add the ginger paste and garlic paste. Sauté for a few seconds. Add the ground masala and sauté on low heat for two to three minutes.
Add one and a half cups of water and bring it to a boil. Add clams, turmeric powder, coconut milk and tamarind pulp. Cook, covered, for five to seven minutes. Garnish with coriander leaves and serve preferably with steamed rice.