Butter-poached trout, burnt leeks and hazelnuts

Put the leeks on a grill tray under the grill set to the highest temperature for 20 mins, turning halfway through. The outer layer of the leeks will be blackened and burnt, and the interior soft enough so that, when squished between finger and thumb, the flesh offers only the slightest resistance. Add the hazelnuts to the tray halfway through, for the final 10 mins of grilling time – you’ll need to keep a close eye on them as the nuts will burn easily. Shake the tray to make sure they’re colouring evenly.

Put the butter in a wide, ovenproof pan over a medium heat – the pan needs to be big enough for the trout to fit in snugly without touching the sides. Allow the butter to melt. Stir with a spatula, scraping the corners and the bottom of the pan to dislodge any milk solids that might have caught. Keep going for 8-10 mins or until the milky residue that’s separated from the butter starts to caramelise – the butter should begin to smell biscuity.

Take the brown butter off the heat and allow to sit for a couple of minutes. Cut a piece of kitchen paper to the same size as the trout. Heavily season the fish, put it skin-side up on the paper and carefully lower it into the butter. If the trout is not completely submerged, pour in enough just-boiled water to cover. Put the pan in the oven at 80C/60C fan for 10 mins.

Roughly chop the roasted nuts, setting aside, and top and tail the leeks, peeling away and discarding the scorched outer leaves. Pull the leek hearts apart into strands and season generously. Remove the pan from the oven and carefully lift the trout out onto a plate. Use a paring knife to gently peel away the skin – it should come away easily. If not, return to the pan and back in the oven for another couple of minutes. The trout should be a blushing pink in the middle and flake easily when nudged.

On a serving plate, arrange the tangle of leeks so they’re spread to the edges. Using a spoon, flake the trout into chunky pieces and arrange on top. Sprinkle over the chopped nuts and top with the watercress. Finally, put the cider vinegar in a mixing bowl and gradually add some of the warm butter skimmed from the pan, until it forms an emulsified sauce. Season, spoon over the salad and serve.