Wash Crabs thoroughly with hot water.
Take Crab along with ½ Tsp. Turmeric Powder and ½ Tsp. Salt and boil it with water for 5 minutes, and discard the water. This step is optional but advisable to follow to avoid allergies, etc that may occur from consuming crab.
Marinate crab with Turmeric Powder and Salt.
Finely chop the remaining Onion.
Heat Oil in a deep-bottom vessel and shallow fry the Crab.
Once done, temper the remaining oil with Bay Leaf, Cinnamon Stick, Black Cardamom, Green Cardamom, Dry Red Chilli, and Sahi Jeera.
Add chopped onion and fry till it turns translucent in color.
Now add Ginger and Garlic Paste, followed by Tomato paste and chopped Green Chilli, and fry till the raw aroma goes and oil comes out from the edges.
Add Turmeric Powder, Red Chilli Powder, Cumin Powder, Coriander Powder, Mace powder, and Nutmeg powder, followed by salt and Sugar, and cook for a minute.
Add Hung curd and cook over a slow flame for 3-4 minutes.
At this point, add fried crabs and cook over the slow flame for 3-4 minutes.
Add ½ cup of water and cook for 2 minutes.
Switch the flame off.