Rub the marination ingredients well on them so that the prawns are fully coated. Leave refrigerated or if cooking on the same day keep it outside till the saas gets prepared.
Till the prawns are marinating, soak the rice and lentils separately and keep aside.
Take a food blender or food processor and grind together chopped onion, garlic cloves, chilly and cumin seeds to a paste and add a tablespoon of water (if required for grinding).
In a non stick pan heat oil. Once the oil is hot add the ground mixture to the hot oil.
Stand a little bit away as the paste will splatter a bit in the oil.
Cook the ground mixture till it turns pinkish brown in color.
Add rice flour and 3 cups of water. Whisk together till you get a smooth curry like paste.
Add it to the ground mixture and let it come to a boil.
Reduce the gas to the lowest flame setting, cover the nonstick pan and let it cook for approx 10 minutes.
Keep stirring intermittently so that the mixture doesn't burn or stick to the bottom of the pan.
In a bowl mix well the egg, vinegar and sugar together.
On a lowest flame setting whisk the paste continuously and slowly drizzle the beaten egg/vinegar/sugar mixture into the saas preparation to create a thick mixture.
Whisk continuously or the egg will poach and cook.
Cover the lid and let the mixture cook together on a lowest flame setting for approx 5 minutes.
If the paste is thick add more water.
Check for salt, herbs, spices etc and add more if required.
Cook the seasoned prawns in the white saas till they’re done. Prawns take only 2 mins but firm white fish may take approx 5-7 minutes to cook. For veg par boil potatoes and add at this stage.
Turn off the flame and add tomatoes and chopped coriander.
The tomatoes need to retain their crunch so don't overcook them.
Keep covered and cook.
Serve hot with khichri or bread or chapati.
Homemade rice flour can be made by using a spice blender or coffee grinder and grind 1/2 cup of raw rice grains till it reaches a smooth flour texture. Store in an airtight container in a dry cool place and use as required in recipes. However if you do not have the time to make rice flour at home it is found easily at most grocery stores. Since I was going to make a record of the recipe for my niece we used rice flour instead of maida.