Preheat your oven to 400 degrees Fahrenheit.
Press the extra firm tofu with a heavy object for 10 minutes to remove excess moisture, then cut into one-inch cubes.
In a small mixing bowl, whisk together the powdered peanut butter, tamari, rice vinegar, grated ginger, minced garlic, sriracha, water, sea salt, and black pepper until smooth.
Place the dry soba noodles, tofu cubes, shelled edamame, and broccoli florets into an 8x8 inch glass baking dish.
Pour the prepared peanut sauce over the ingredients, ensuring the noodles are mostly submerged in the liquid.
Cover the dish tightly with aluminum foil to ensure the steam cooks the noodles and vegetables properly.
Bake for 22 minutes, then remove from the oven and let the dish sit, still covered, for an additional 5 minutes.
Remove the foil, stir the contents thoroughly to coat everything in the thickened sauce, and serve immediately.