In a small saucepan saute the onion and garlic in oil until tender (without burning the garlic) and set aside to cool.
Combine tuna, eggs, bread crumbs, onion mixture, and hot sauce, in a medium bowl and mix well. Shape into 4 patties (mixture will be very soft and delicate). Refrigerate for 30 minutes to make the patties easier to handle. Coat a nonstick skillet with cooking spray and fry tuna patties for about 3 to 4 minutes per side, or until cooked through. These are fragile, so be careful when turning them. Serve on buns with tomato slices, Brie and kosher pickles. You may decide to serve wasabi on the side.