An elegant meal which combines light tomato with succulent seafood.
Heat the oil in a large sauté pan or shallow casserole. Add the leek and fennel with a pinch of salt. Cover and sweat for 5 minutes, then uncover and fry for another 5 minutes until soft and turning golden. Add the paprika and tomato purée, then fry for 2 more minutes.
Stir in the vinegar and tomatoes, fry for 1 minute, then add the fish stock and simmer for 5 minutes. Remove the shells from the prawns, leaving the tails on, if liked. Nestle in the prawns and fish, then cover and simmer for 5 minutes, until the fish is cooked right through and the prawns are a pinky orange colour.
Check the seasoning (it will probably benefit from a pinch of sugar or honey) and serve with a dollop of mayonnaise or crème fraîche, if liked.