Season the tuna pieces with salt and pepper. Coat lightly on all sides with bread crumbs. Heat olive oil in a large heavy frypan over high heat. The pan should be as hot as you can get it. Place the tuna in the pan and sear on each side for about 45 seconds for small portions, or 1 minute for large. Remove from pan. The tuna will be very rare.
Slice each steak into 5mm thick slices and fan out on a serving plate. Enjoy plain or with the condiments of your choice.