Preheat oven to 400°F. Trim stems and remove wilted leaves from Brussels sprouts; rinse under cold water. In a large bowl, combine water, salt, sugar and soy sauce, stirring until all of the sugar and salt dissolve. Add sprouts to the brine mixture, making sure sprouts are submerged. Brine for 1 hour. Drain the Brussels sprouts, do not rinse. Toss the sprouts with olive oil and black pepper in a large baking dish. Bake for 35-40 minutes, or until crisp on the outside and tender on the inside.