1. Dip the shrimp in boiling water for a few seconds, then drain into a colander.
2. Cut the tomato roughly and mix it. Add the ketchup, mustard and coriander. Cook the sliced onions in the juice of two lemons and mix and mix with the mixture.
3. Squeeze the remaining three lemons and pour over the shrimp. Let stand for 5 to 10 minutes then pour into the preparation.
4. Add salt and pepper to taste.
5. Put in the fridge and serve very fresh in soup plates.