Dry roast red chilies, peppercorns, cumin seeds and coriander seeds for a min on low flame. Remove from the heat and allow to cool. Grind it in a mixer to coarse powder. Add chopped pearl onions and grind again without adding water. Keep it aside.
Marinate leg pieces with turmeric powder for 20 mins. Break the leg pieces using a pestle or cleaned stone and keep aside. Heat oil in a pressure cooker. Fry cloves and cinnamon. Add chopped onions and saute a while.
Now, Add chopped tomatoes and ginger-garlic paste. Mash the pulp. Add leg pieces, ground masala paste and salt to taste. Mix well everything and add 5-6 cup water. Close the lid and pressure cook for 8-9 whistles. Remove from the heat.
Once pressure settles, stir well rasam. Heat 1 or 2 tsp oil in a pan or kadhai. Temper fennel seeds and curry leaves. Add rasam to it and allow to boil. Garnish with chopped coriander and serve hot. You can sprinkle 1 tsp lemon juice at the time of serving.
We are breaking the leg pieces of crabs so that the crab meat combines well with the masala.
You can store this rasam in refrigerator for 2-3 days. Before serving, reheat it and Enjoy