Roast salmon, skagen butter and cardamom caramel potatoes

To make the skagen butter, combine all the ingredients in a bowl, stirring well. Season with plenty of salt and white pepper. Spoon in a log shape onto some plastic wrap, then roll up, twisting the ends of the plastic to make a firm sausage shape. Refrigerate until ready to serve. Now preheat the oven to 190C (375F/gas 5). Then cook the potatoes in salted boiling water for 15 minutes, or until tender. Drain well, cover to keep warm and set aside. 

To make the creamed peas, cook the peas in boiling water for about 5 minutes, or until tender, then drain well. Combine the peas with the butter and sour cream in a food processor and blend until smooth. Tip into a small saucepan and season to taste with salt and a little white pepper. Cover and set aside until ready to serve. 

Rinse the salmon inside and out and pat dry with paper towels or a very clean tea towel (dish towel). Then insert half the onion, lemon slices and dill sprigs in the cavity. Rub all over with a little olive oil and sprinkle with sea salt. Next wrap the head and tail with foil. Make a bed of the remaining onion and lemon in the base of the tin and lay a long piece of muslin (cheesecloth) over the top, making sure it hangs a little over the two short edges – this will act as handles for removing the fish later on. Place the fish on top of the cloth and pour the wine and 250ml (9fl oz /1 cup) of water into the base of the tin. Cook the fish in the oven for a bout 45 minutes, basting regularly with the juices, until the dorsal fin is very loose or comes off when jiggled. At this stage the fish should be cooked through but still quite pink and translucent in the centre of the fillet.

Meanwhile, to caramelise the potatoes, place the sugar in a large heavy-based frying pan over medium-high heat, stirring occasionally until the sugar has melted. Bring to the boil, then reduce the heat and simmer for 5 minutes, or until it turns golden. Carefully stir in the butter and cardamom – the caramel will become lumpy but will melt as you continue to cook. Now add the potatoes and shake the pan for 6 minutes, or until the potatoes are caramelised and heated through. Season to taste and keep warm. 

Gently reheat the creamed peas, if necessary. Lift the salmon out of the roasting tin using the muslin to help you. Carefully transfer onto a warmed serving platter, gently sliding the cloth from under it. If you find it difficult to remove the cloth, simply use some sharp scissors to cut around the edges close to the fish. Now remove the foil from the head and tail and carefully peel back the skin from the top side of the fish, starting at the head end and pulling towards the tail; discard the skin. Finally serve portions of the fish on a bed of the creamed peas with a dollop of the skagen butter on top and the potatoes on the side.