In a bowl, combine sesame seeds, sesame oil, soy sauce, and salt. Using a sharp knife, cut the tuna into ¼-inch cubes. Add the tuna to the bowl and mix well. Let it sit for about 15 minutes. Place a little wasabi sauce on the sesame cracker. Then, put a spoonful of tuna on each cracker to serve. Add some segments of a blood orange. Garnish with some edible flowers and black sesame seeds, and enjoy!