Ingredients
For the sauce
500g/1lb 2oz fresh mussels in their shells
2 shallots, finely sliced
olive oil
250ml/9fl oz white wine
250ml/9fl oz single cream
squeeze lemon juice
salt and freshly ground black pepper
5cm/2in piece fresh horseradish root
For the potatoes
200g/8oz Charlotte potatoes
bunch chives, chopped
For the salmon
4 pieces of wild salmon fillet, each 120g/4½oz, skin on
100g/4oz freshly shelled peas
50g/2oz pea shoots
salt and freshly ground black pepper
sqeeze lemon juice
drizzle olive oil

Method
1. To make the sauce, prepare the mussels by washing them under cold water and removing the 'beards'. Drain. Discard any that do not close when lightly tapped. In a heavy-bottomed pan, cook the shallots in a little olive oil until translucent. Add the mussels and pour on the wine. Place a lid on the pan and cook for 3-4 minutes or until the mussels have opened. (Discard any that do not open.) Drain the mussels in a colander set over a bowl. Pour the liquid from the bowl into a small pan and set aside. Pick the mussels out of their shells and keep, covered, in the fridge.
2. To make the sauce, bring the reserved mussel liquid to the boil. Add the cream and simmer for 5-6 minutes until reduced slightly. It should not be too thick, but more soupy. Season with salt, freshly ground black pepper and a squeeze of lemon juice. Remove from the heat. Grate in the fresh horseradish and leave to cool. When cool, taste the sauce. If the horseradish flavour is strong enough, strain through a fine sieve and leave to one side. If not, leave a little longer for the flavour to develop before straining.
3. For the potatoes, cook the whole potatoes in boiling salted water for 10-12 minutes or until tender. Drain and leave to cool. When cool, peel off the skins and put the potatoes back into the saucepan. Crush the potatoes with a fork. Season with salt and freshly ground pepper, and add the chopped chives. Keep warm.
4. Preheat the oven to 180C/350F/Gas 4.
5. For the salmon, season the salmon with salt and freshly ground pepper. Heat a non-stick, ovenproof frying pan, then add a splash of olive oil and cook the salmon skin-side down for two minutes, without turning. Place the pan in the oven to cook for 3-4 minutes.
6. Meanwhile, heat a little of the horseradish cream sauce in a pan. Add the peas and cook for one minute, then add the mussels just to warm through. Heat the remaining sauce in another pan. Season the pea shoots with salt, pepper, lemon juice and a drizzle of olive oil.
7. For each serving, place a chefs' ring, about 4cm/1½in diameter, in the middle of a shallow bowl. Spoon the crushed potatoes into the ring, lightly packing them. Remove the ring. Scatter the mussels and peas around the potato and place a salmon fillet, skin-side up, on top. Scatter the pea shoots on top of the mussels and peas, then finish with a light drizzle of the warm horseradish cream sauce all around.