Step 1

Toast the nigella seeds, fennel seeds, cumin seeds, mustard seeds and fenugreek seeds till fragrant and the color changes a little (approx. for 2 minutes) and crush coarsely.

Step 2

In a blender, puree the tomatoes. Finely chop the onions. Slit the green chilies lengthwise and deseed the chilies.

Step 3

Heat the oil in a non-stick saucepan and gently fry the seeds for 30 seconds.

Step 4

Add the onion and fry for about 10 minutes on low flame, until lightly golden in color. Add the garlic and ginger pastes and the chillies. Saute for 1 minute, then add the turmeric, coriander and salt.

Step 5

Pour in the pureed tomatoes and simmer until the oil rises to the surface - about 10 minutes.

Step 6

Add the prawns and the water. Bring to the boil and then reduce the heat to a slow simmer. Cover and simmer for 3-4 minutes, until the prawns are nearly cooked.

Step 7

Remove the cover and stir over a high heat until the sauce thickens. Stir in the remaining ingredients: pepper, lemon juice and fresh coriander. Serve hot.