1. Soak 20 gms mustard seeds in hot water for atleast 2 hours. alternatively, you can also soak them in regular water, overnight.
2. Shell and devein 300 gms prawns. keep the heads intact; they have all the flavour. the tails add a visual flair, so we keep them as well.
3. Strain the mustard seeds and add to a grinder jar, along with 12 gms salt and 3 chopped green chillies.
4. Blitz into a fine paste by adding 50 gms water. scrape down the sides as often as you need, and grind again. repeat this process till you have a smooth paste.
5. Now, while the mustard paste is still in the grinder, add 15 gms sugar, 3 gms turmeric powder, and 20 gms chopped coconut. blitz again till the coconut breaks down.
6. Transfer this paste to a microwave-safe bowl. add in 40 gms yogurt and mix till uniform. fold in the prawns. top off with 25 gms mustard oil and a slit green chilli. cover the bowl with a plastic wrap. microwave for 5 minutes.
If you are not using microwave oven
1. Place the prawns-and-mustard mixture in a covered steel container (such as a water-tight tiffin box).
2. Bring an inch of water to boil in your pressure cooker or boiling pot.
3. Now, carefully lower the tiffin box in the water. be sure to check that the water level does not reach the lid of your tiffin box. if it does, throw away some of the water till it clears the lid.
4. Cover up the pot / pressure cooker and allow the prawns to steam for 10–12 minutes in the boiling pot or for one whistle in a pressure cooker.