Place the cleaned prawns in a bowl and add turmeric powder. Season with salt and mix well. Keep for 15 minutes and then fry the prawns till just opaque in mustard oil. Keep aside.

Parboil the potatoes with a little bit of salt, keep aside.

In the same pan/kadai, heat more mustard oil and add the whole spices (cloves, cardamom, cinnamon, bay leaf and chillies). Also add the cumin seeds and allow to splutter lightly on low heat.

To this, add the onion and ginger paste. Mix well and sauté till the rawness of the onion goes away and takes on a light brown colour.

Next add the tomato puree; mix well and allow to cook for 2-3 minutes till the excess water evaporates and the tomato mixture is cooked down.

Mix the red chilli, cumin, coriander and turmeric powder with a little bit of water to form a paste; add this to the tomato mixture and mix well to combine.

Cook for a minute or two till oil starts to appear at the sides and then add ½ cup water. Bring to boil and add the prawns and potatoes. Taste and season with salt if necessary.

Lower heat and cook till the prawns are done. Cover and keep for at least 15 minutes before serving.

Garnish with chopped coriander leaves and slit green chillies.