1 pound block of Yellowfin tuna
1/2 cup real soy sauce
1/2 teaspoon grated orange zest
1/2 cup orange juice
3/4 tablespoon sugar
1 garlic clove, crushed
1-1/2 teaspoons wasabi paste
1/2 cup sesame seeds
1. Cut block of tuna into large rectangular chunks. Trim any parts that are almost black; those aren't very good because they are the bloodspots. DO NOT, I REPEAT DO NOT slice the chunks into steaks or slices...leave the blocks as-is.
2. In a bowl, mix the soy sauce with the sugar, orange zest, orange juice, crushed garlic and wasabi paste together to form into a marinade.
3. Drop in the chunks of tuna, making sure it's all covered. Toss around if it's not completely covered, and let stand in refrigerator for about an hour (Note: Do not marinade for more than four hours or else the tuna will lose its natural flavour!)
4. While the tuna marinates, start up your charcoal grill (or the barbeque if you don't have a charcoal grill, brick spit, etc.)
5. Remove the tuna from the marinade after removing from the refrigerator, and then roll them onto a plate covered with sesame seeds. Roll around until all of the sides are covered.
6. Once ready for the grill, place onto the top of the greased grille...if the coals are hot, then cook the first side for about 30 seconds. Then turn around and cook the next side for another 30 seconds, and so on. Best way to tell is when the sesame seeds are charred.
7. Place on a plate, and slice each slice thinly and serve immediately. A little pickled ginger and wasabi, or maybe some soy sauce, or even a small touch of lemon, or even a bit of a lime-ginger sauce all serve well as accompaniments.