Add the "beef slices" to a medium bowl or deep plate and cover with boiling water. Let it sit for 30 minutes to rehydrate the slices.
Drain and rinse 2-3 times, squeezing the slices to remove as much water as possible. Cut the slices into thinner strips. Transfer the strips to a bowl, add the soy sauce and black pepper and stir to coat. Let marinate for about 10 minutes.
Heat a tablespoon of oil in a non-stick skillet. Add the tofu cut into matchsticks and fry on each side for 2-3 minutes, or until golden brown. Remove from the skillet and place the tofu on a kitchen paper towel to remove excess oil.
To the same skillet, add the remaining tablespoon of oil and the chopped scallions and sauté for 1-2 minutes. Add the marinated "beef strips" and sauté for 3-5 minutes. Next, add the chopped veggies and sauté for another 5-7 minutes, or until just tender.
In the meantime, bring a large pot of water to a boil and cook the noodles according to the package instructions. Save two tablespoons of the cooking water to dilute the char siu sauce.
Add the drained noodles and fried tofu to the skillet. Pour in the diluted char siu sauce and stir to coat the noodles and veggies with the sauce. Cook for 1 more minute.
Top with chopped cilantro and serve immediately!