Never had bluefin, but I love ahi tuna. Simple is usually better with what tuna recipes I've tried. My favorite way to cook ahi is to rub it with some sesame oil, then salt and pepper, roll in a mixture of black and white sesame seeds and sear on each side to rare/medium rare. I usually make a sesame oil/soy/scallion/ginger/garlic dipping sauce.
...Half a yard full of crap to cook on like everybody else...
Just a hungry hillbilly lookin for a dead critter to cook
in one throwdown,