Zedd, after checking my notes on my computer at work I found that I was mistaken about marinating the tuna overnight in olive oil. Apparently an hour is sufficient. Following are the exact notes from the class:
"Olive oil�extra-virgin olive oil, to be exact�solved our problem. We discovered that marinating the fish in extra-virgin olive for at least an hour produced a remarkably moist grilled fish. Our next question was, why? According to food scientist Shirley Corriher, the oil was tenderizing the fish in much the same way that marbling (strands of white fat running through the meat) tenderizes beef. The oil coats the strands of protein, making a tuna steak feel moist in the mouth even after most of the moisture has been cooked out of it."
Further they suggested serving it with a fruit salsa. I made the recipe using mangoes and it was lovely with the fish:
SIMPLE PEACH SALSA
Makes about 3 cups
If you don't have peaches, you can substitute a number of other yellow-orange fruits, including mangoes, pineapples, and papaya.
2 ripe but not mushy peaches, pitted and chopped coarse
1 small red bell pepper, cored, seeded, and sliced thin
1 small red onion, cut into long, thin slices
1/4 cup chopped fresh parsley leaves
1 medium clove garlic, minced
1/4 cup pineapple juice
6 tablespoons juice from 3 medium limes
1 jalape�o or other medium hot chile pepper, minced
Salt and ground black pepper
Mix all ingredients, including salt and pepper to taste, in
medium bowl. Cover and refrigerate to blend flavors, at least 1 hour or up to 4 days.