Grind all in ingredients to be ground with water till you get a very fine paste.
Heat an earthern pot or a pan of your choice and put oil in it.
Once heated, add the sliced onions and saute till they are transluscent.
Put in the tomatoes and stir till the tomatoes slightly softens.
Add the turmeric and chilli powder and mix well for a minute.
Add the ground paste and stir well.
Adjust the consistency by adding water.
Once it comes to a boil, add the shrimp powder, stir and turn off the heat.
In another pan, heat the oil and add mustard seeds.
Once it splutters, add the curry leaves and the shallots and fry till the shallots turn slightly brown in colour.
Turn off the heat and then add it to the curry.
Serve hot with Rice