Directions

1. Place the block of tofu onto a plate, then place another plate on top. Set a 3 to 5 pound weight on top (a container filled with water works well). Press the tofu for 20 to 30 minutes, the drain off and discard the accumulated liquid.
2. Preheat an oven to 400 degrees F (200 degrees C). Grease a baking sheet.
3. Cut the block of tofu down the middle, then widthwise into 1/4 inch thick squares. Arrange on the prepared baking sheet.
4. Bake in the preheated oven for 6 minutes, the turn the pieces over, and continue baking 5 minutes more. Remove the baking sheet from the oven, and allow to cool. Once the tofu is cool enough to handle, cut into 1/4 inch dice.
5. Heat the vegetable oil in a large skillet over medium heat. Stir in the onion and green pepper; cook and stir until the onion has softened and turned translucent, about 5 minutes. Stir in the diced tofu, ketchup, sugar, mustard, and vinegar; season to taste with salt. Bring to a simmer over medium-high heat, then reduce the heat to medium-low, and simmer for 10 minutes. Serve on the whole wheat hamburger buns.