Soak tomatoes in very hot tap water until softened. Drain and chop. Set aside. In a nonstick, 10 inch (25 cm) skillet, heat butter over medium heat. Add onions and cook until almost brown, without stirring, about 7 minutes. Stir and continue cooking until onions are golden brown. Add vinegar and cook until brown. Season with salt and pepper. Let cool. Whisk eggs and water; stir in cooled onions. Spray a 9 inch (23 cm) square pan with vegetable spray. Pour in egg mixture. Bake at 180oC (350 oF) for 15 minutes or until set. Let stand a few minutes before cutting into 8 triangles. Place lettuce leaf and two triangles overlapping on each roll bottom. Top with 2 tbsp (30 mL) bacon pieces, 1 tbsp (15 mL) dried tomatoes, 1 slice cheese, 1 lettuce leaf and remaining half roll.