Pistachio-Crusted Cod with Beurre Blanc

Blitz the pistachios, parsley and tarragon in a food processor until the mixture resembles coarse sand — do not over-process into a paste. Transfer to a bowl, work in the softened butter and Dijon mustard with a fork, and season with half the salt and pepper to form a cohesive, spreadable crust mixture.

Line a baking tray with parchment. Season the cod fillets on both sides with the remaining salt and pepper. Divide the pistachio crust evenly between the fillets and press firmly onto the top surface of each in an even layer roughly 5mm thick. Refrigerate uncovered for 20 minutes so the crust firms up and adheres.

Preheat your oven to 200°C fan (220°C conventional). While the oven heats, combine the minced shallots, white wine and white wine vinegar in a small heavy-bottomed saucepan. Bring to a vigorous boil over medium-high heat, then reduce to a lively simmer and cook until the liquid has reduced to approximately 2 tablespoons of syrupy, jammy shallots — about 12–14 minutes.

Heat the olive oil in an ovenproof frying pan over medium-high heat until shimmering. Sear the base of the cod fillets (crust side up) for 90 seconds until the underside is lightly golden and opaque by 3–4mm up the sides.

Transfer the pan to the preheated oven and roast for 10–12 minutes, until the pistachio crust is deep golden and the cod reaches an internal temperature of 63°C on a meat thermometer inserted into the thickest part. Rest on the tray for 2 minutes.

Return the shallot reduction to the lowest possible heat and stir in the double cream. Add the cold butter cubes three or four at a time, whisking constantly and waiting for each addition to be fully incorporated before adding the next — the sauce should look creamy and pale, never oily or broken. Do not let the pan exceed 60°C.

Season the beurre blanc with salt, white pepper and lemon juice. Strain through a fine-mesh sieve if you prefer a smooth sauce, or leave the shallots in for a more rustic presentation. Spoon immediately onto warmed plates, place a cod fillet on top, and serve at once.