Chicken Ballotine with Pistachio and Tarragon Mousseline

Debone the chicken legs if not already done: lay each leg skin-side down and, using a sharp boning knife, cut along the thigh bone and drumstick, scraping the meat away until the bone lifts out in one piece. Keep the skin intact and as large as possible, then refrigerate the boned legs while you make the mousseline.

Pulse the chilled chicken breast cubes in a food processor for about 30 seconds until a smooth paste forms.

Add the egg white, 1 teaspoon of the salt, the white pepper, nutmeg, and Dijon mustard, and process for a further 20 seconds until completely homogenous.

With the processor still running, pour in the cold double cream in a slow, steady stream and stop the instant it's incorporated — overprocessing will break the emulsion and leave the mousseline grainy.

Scrape the mousseline into a bowl set over ice and fold in the toasted pistachios, parsley, and tarragon by hand. Poach a small teaspoon of the farce in simmering salted water to taste it, then adjust the seasoning.

Lay each boned leg skin-side down on a sheet of cling film and season the flesh with the remaining ½ teaspoon salt. Divide the mousseline evenly among the four legs, mounding it in the centre of each.

Roll each leg tightly around its filling using the cling film to shape a compact cylinder, twisting the ends firmly to seal, then tie off each end with kitchen twine for a tight, even shape.

Refrigerate the ballotines for at least 2 hours, until the farce is fully set and each roll holds its shape.

Combine the chicken stock, carrot, celery, onion, bay leaves, and thyme in a wide saucepan large enough to hold all four ballotines, and bring to a gentle simmer over medium heat.

Lower the heat until the stock settles at 80°C, with only the occasional lazy bubble, then lower the cling-film-wrapped ballotines into the stock.

Poach for 25–30 minutes, turning once halfway through, until a meat thermometer inserted through the cling film into the centre of the farce reads 74°C.

Transfer the ballotines to a plate and rest for 10 minutes, then carefully remove the cling film and pat the skin dry with kitchen paper.

Heat the neutral oil in a heavy-based skillet over high heat until shimmering. Add the ballotines seam-side down and sear for 2 minutes until deep golden.

Turn to sear all sides, about 1–2 minutes per side, then add the butter and baste continuously for a final minute until the skin is lacquered and mahogany brown.

Rest the ballotines on a wire rack for 5 minutes, then slice each into three medallions on the diagonal. Finish with flaky sea salt and serve with the strained poaching stock, reduced by half, as a jus.