My favorite fast marinade is 1 cup mayonaise and 1 cup good Teriyaki (like Very Yeri Teriyaki)You can add sliced green onion or fresh grated ginger if you like it. I add a bunch of fresh cracked pepper too. Put it in a gallon ziplock, mix it all together and put your chunks in there. I just cut the loins into 3 or 4 pieces so they are pretty thick. Lay it on the counter for about 45 minutes and bbq on medium high heat about 4 minutes per side. It cooks all the way through and is moist and delicious. You don't taste the mayo at all - I think it cooks off and just helps to keep the fish moist.