1. Preheat oven to 350 degrees Celsius and line a cookie sheet with parchment paper
2. Cut tray buns through the middle but keep them all intact.
3. In a large wok or non-stick skillet, heat oil on medium heat.
4. In a large bowl, crumble extra firm tofu until they resemble ground beef and are in small pieces.
5. Add tofu and onions to the wok/skillet, along with salt, pepper, garlic powder. Toss to combine. Then add tomato sauce, water, ketchup, mustard, Worcestershire sauce, dark soy sauce, water, and mix thoroughly. Cook for another 10 minutes.
6. Compile your sloppy joes by first adding a layer of cheese to the bottom bun, then your sloppy joe mixture, then another layer of cheese, and top with the top part of the bun.
7. Brush tops of bun with melted butter and sprinkle sesame seeds. Bake for 5-7 minutes or until cheese is melted.