Roast Tuna with Orange and Anchovies

In a large, non-metallic bowl, combine the orange juice, 2 tablespoons of the olive oil, the anchovies and their oil, and the red pepper flakes and season with pepper. Add the tuna and spoon the marinade over it. Cover with cling film and marinate in the refrigerator for 2 hours, turning the tuna occasionally. Remove from the refrigerator about 20 minutes before cooking to return the fish to room temperature.

Remove the tuna from the marinade, reserving the marinade, and wipe dry. Heat the remaining oil in a large frying pan over a high heat. Add the tuna and sear for 1 minute on each side until lightly browned and crisp. Place in a roasting tin. Cover the tin tightly with foil.

Roast in a preheated oven, 220ºC / 425ºF / Gas Mark 7, for 8 minutes for medium-rare and 10 minutes for medium-well done. Remove from the oven and set aside to rest for 2 minutes before slicing.

Meanwhile, place the marinade in a small saucepan over a high heat and bring to a rolling boil. Boil for 2 minutes.

Transfer the tuna to a serving platter and carve into thick slices, which will probably break into chunks as you cut them. Serve the sauce separately for spooning over.