Dry the seabass on kitchen paper, season with salt and pepper and lightly dust the skin with flour. Heat the olive oil in a large non-stick frying pan and add the butter. Once the butter begins to sizzle place the fish in skin side down. The fish may need to be gently pressed down with a fish slice to stop it curling up. Leave to cook for 6 to 7 minutes or until the skin is crisp and coloured. Turn it over and remove from the heat, the residual heat in the pan will continue to cook the fish.
For the leek carbonara
Heat a large saucepan and add the bacon. Fry for a few minutes until it’s golden and crisp.
Transfer the bacon to a plate and pour away any excess fat from the pan. Add the butter and once melted stir in the leeks along with 3 tbsp of water. Cover the leeks and leave to steam for a few minutes until tender. Pour over the cream and simmer until lightly thickened.
Stir through the parmesan and bacon. To serve, spoon the leeks onto a serving plate and top with the seabass.