Tasty South Indian-style Crab Roast Recipe

Crab – 1 kg
Onion – 3
Green chilli – 2-3
Ginger-garlic, crushed – 2 tbsp
Tomato – 2
Coriander powder – 2 tbsp
Red chilli powder – 1 tsp
Turmeric powder – 1/4 tsp
Pepper powder – 1 tbsp
Curry leaves – 2 sprigs
Salt
Water
Crushed pepper – 1 tbsp
Oil
Mustard seeds – 1tsp
Shallots – 10
Red chilli – 3
Curry leaves – 1 sprig