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
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.