Roughly chop the prawns while still in their shells. Heat some olive oil in a large saucepan, add the prawns and fry over a high heat for a few minutes until lightly coloured.
Reduce the heat, stir the onion and carrot into the prawns and cook for 5-6 minutes. Pour in the brandy and boil until almost dry. Stir in the tomato purée, chopped tomatoes and tarragon an