Begin by making the tofu. Coat the bottom of a medium skillet with the oil and place it over medium heat.
Add the tofu cubes in a single layer. Cook the tofu for about 10 minutes, flipping the pieces once or twice so they brown on multiple sides.
While the tofu cooks, stir the soy sauce, ginger, and black pepper together in a small bowl.
Pour the soy sauce mixture over the tofu and flip the pieces a few times to distribute the ingredients. Cook the tofu for a minute or two longer, until most of the liquid dries up. Transfer the tofu to a plate when it's done.
While the tofu cooks, bring a large pot of water to a boil. Add the noodles and set the timer for one minute less than the package instructions specify. When the timer goes off, add the broccoli. Cook the broccoli and noodles together for one minute, then drain them together into a colander and return them to the pot. Add the bell pepper.
To make the sauce, whisk the tahini, soy sauce, vinegar, sriracha, maple syrup, sesame oil, and garlic together in a small bowl. Thin the sauce with water, adding as much as you need to achieve a creamy but pourable consistency (Note 2). Taste-test the sauce and adjust any seasonings to suit your taste.
Add the tofu to the pot with the noodles, then pour in the sauce. Stir everything up to coat everything with the sauce.
Divide the noodles, veggies, and tofu among bowls or plates, then top each one with a sprinkle of sesame seeds and scallions. Serve.