I don't understand why so many people like their tuna so over cooked and dry. Tuna has fat that melts at around human body temperature, and has rich flavorful red meat. My personal favorite way to eat tuna is to heat up a pan with a little olive oil, paint a room-temp tuna steak with a beaten egg, and then roll it in panko. And when I "fry" it, I basically just crisp the panko and leave 80% of the tuna still raw. It's like a pants party in my mouth.
I marinade to the beat of a different drummer.