Finely chop the tuna and salmon. In a large mixing bowl combine tuna and salmon with cilantro, lime juice, garlic, 4 teaspoons of the olive oil, the ginger, chili sauce, wasabi, salt, and pepper. Shape into 6 patties about 3/4 inch thick.
Place burger patties on the lightly oiled rack of the grill directly over medium heat. Grill for 10 to 12 minutes or until an instant-read thermometer inserted in centers registers 160 degree F, turning burgers once halfway through grilling. Brush the flatbread with remaining olive oil. Toast on grill rack for 1 to 2 minutes or until golden brown.
Serve burgers folded in flatbread and topped with Aquavit Green Cabbage Slaw and, if desired, yellow tomato slices. Makes 6 burgers.
Aquavit Green Cabbage Slaw
Combine yogurt, garlic, parsley, dill and lime juice in a food processor or blender container. Add salt and pepper. Cover and process or blend until smooth. Toss with Napa cabbage in a large mixing bowl. Cover and refrigerate until using or overnight. Makes 4 to 6 servings.