Name: Halibut with mussels, potatoes and lettuce
Total time: 1 h 30 min
Ingredients: 1 halibut, large, filleted and trimmings reserved; 50g of light brown sugar; 100g of sea salt; 1l water; 1 egg white; 100g of double cream; 3g of fine sea salt; 50g of unsalted butter, softened; 1 tsp dulse, finely chopped; 50ml of smoked rapeseed oil; 3 banana shallots, finely chopped; 2kg mussels, cleaned and washed; 300ml of white wine; 2 tsp Dijon mustard; 2 egg yolks; 18 small potatoes; 2l olive oil; 2 bay leaves; 1 lemon, juiced; 1 butter lettuce, halved and any damaged outer leaves removed

Main
Medium
6
1 hour 30 minutes

PT1H30M

Don't be fooled by the simple presentation and title of this incredible recipe – there's some serious technique on show. The halibut is portioned and brined, with all the trimmings used to make a rich mousse studded with mussels that's spread on top before steaming. The sauce, made from the mussel cooking liquor, is thickened with egg and seaweed butter to create a silky custard texture, and the potatoes are cooked confit in olive oil. Quite simply stunning.

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Halibut

1 halibut , large, filleted and trimmings reserved
50g of light brown sugar
100g of sea salt
1l water

Mousse

1 egg white
100g of double cream
3g of fine sea salt

velouté

50g of unsalted butter , softened
1 tsp dulse, finely chopped
50ml of smoked rapeseed oil
3 banana shallots , finely chopped
2kg mussels , cleaned and washed
300ml of white wine
2 tsp Dijon mustard
2 egg yolks

to garnish

18 small potatoes
2l olive oil
2 bay leaves
1 lemon , juiced
1 butter lettuce , halved and any damaged outer leaves removed

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To begin, cut your halibut fillets into 6 equal portions, ensuring you save 200g of trimmings from the skirt and tail (you can ask your fishmonger to do this if preferred). Combine the water, sugar and salt in a pan and heat until the sugar and salt has dissolved. Leave to cool completely, then submerge the halibut portions in the brine and leave to brine for 6 minutes. Drain, rinse, pat dry and then store in the fridge until later

1 halibut , large, filleted and trimmings reserved
1l water
50g of light brown sugar
100g of sea salt

For the sauce, blend or whip the butter and dulse together until fully combined, then set aside in the fridge. Heat the smoked oil in a heavy-bottomed saucepan, then cook the shallots for 5 minutes until soft. Add the mussels and white wine, then turn the heat up to high and cover. Allow to steam for 2-3 minutes until the mussels open, then strain through a fine sieve (or even better, a coffee filter). Reserve the liquid and pick the meat from the mussels. Finely dice the mussel meat and set aside for the mousse

50g of unsalted butter , softened
1 tsp dulse, finely chopped
50ml of smoked rapeseed oil
3 banana shallots , finely chopped
2kg mussels , cleaned and washed
300ml of white wine

Return the mussel cooking liquor to a separate pan and reduce one-third. Set aside

To make the mousse, add the reserved halibut trimmings and salt to a chilled blender jug and blitz until smooth. Blitz in the egg white, then finally blend in the double cream. Pass through a fine sieve into a bowl and fold through enough of the reserved diced mussel meat to create a pipeable mousse. Transfer to a piping bag

3g of fine sea salt
1 egg white
100g of double cream

Place each halibut portion on a small piece of baking paper, then pipe the mousse on top of it, around 5mm thick. Refrigerate until needed

For the garnish, fill a saucepan with the olive oil over a medium heat. Add the bay leaves, then the potatoes. The oil wants to be almost boiling, with the potatoes being gently cooked for around 20 minutes. Once cooked, lift the potatoes out of the oil (reserving the oil) and leave to cool slightly before peeling

2l olive oil
2 bay leaves
18 small potatoes

While the potatoes cool, set up a steamer (or steam oven) and cook the halibut fillets until their internal temperature reaches 50°C. Depending on how hot your steamer is, this should take 5-8 minutes. Leave to rest for a few minutes

To finish the sauce, reheat the mussel liquor and whisk in the dulse butter and mustard over a medium heat until it emulsifies. Pour a little of the sauce over the egg yolks to temper, then whisk this back into the pan over a low heat until thickened and smooth (do not allow to boil, otherwise the eggs will scramble)

2 tsp Dijon mustard
2 egg yolks

To serve, reheat the potatoes in the warm olive oil for 30 seconds, then drain. Divide the lettuce into leaves and add to the warm olive oil leftover from cooking the potatoes. Drain, then dress the leaves and potatoes with a pinch of salt. Add a squeeze of lemon to the lettuce, cut each halibut portion in half, then place 2 halves on each plate. Garnish each dish with the lettuce leaves, 3 potatoes and 3 tablespoons of the sauce