In pan heat oil. Now add mustard seed once the mustard seed stop splattering add crushed garlic and sauté unitl raw smell is gone.
Now add onion, curry leaves and sauté until it turns translucent.
Now add tomato and sauté until they become mushy. Now add the turmeric powder, chili powder, coriander powder, salt and sauté until the raw smell is gone and oil seperates.. NOTE: don't burn if you need to sprinkle some water.
Now add the green chili, prawns and mix well. Cook this until the prawns are cooked and oil seperates.
Before you remove from stove. Add with coriander leaves and mix well.