1. To make Crispy Tofu: Cut tofu block into two broad slabs. Wrap tofu slabs in paper towels, and place between two cutting boards. Weight top cutting board with soup cans, and press 30 minutes. Unwrap tofu, and cut into 1-inch cubes.
2. Combine soy sauce, vinegar, mirin, oil, garlic, and ginger in resealable container. Add tofu, and toss to coat. Marinate 30 minutes, or overnight. (Tofu should absorb all liquid.)
3. Preheat oven to 350°F, and coat baking sheet with cooking spray. Sift cornstarch over tofu, and turn to coat evenly. Spread tofu on baking sheet. Bake 30 to 40 minutes, or until firm and crispy, turning several times to brown all sides.
4. To make Sauce: Whisk together broth, sugar, soy sauce, mirin, vinegar, sesame oil, cornstarch, tomato paste, and sambal oelek (if using) in small bowl. Set aside.
5. Heat vegetable oil in wok or large skillet over medium-high heat. Add green onions, garlic, and ginger, and stir-fry 1 minute. Add broth mixture, and cook 1 minute, or until thickened. Stir in Tofu. Serve with steamed broccoli and rice.