Place cubed tofu into a medium bowl with corn starch and 1 tsp salt. Toss to coat.
Make sauce: mix sake, tonkatsu sauce, soy sauce, and mirin in a small bowl. Stir to combine.
Cook noodles according to package directions and drain.
Heat wok over medium-high heat. Add vegetable and sesame oils. When hot, add tofu cubes in a single layer - cook in batches if needed. Cook until lightly browned, about 2 minutes per side. Remove to a paper towel lined plate. Carefully wipe wok free of oil.
Turn heat under wok down to medium. Add bacon. Cook 10 minutes or until beginning to crisp. Move to sides of wok, leaving center open.
Increase heat to medium-high. Add onions to middle of wok. Cook 2 minutes. Push out to edges. Add carrots to middle of wok. Cook 2 minutes. Push to edges. Add cabbage and remaining salt in the same manner and cook 4 minutes, then mushrooms for 2 minutes. Add garlic and cook for 30 seconds, stirring to combine.
Add noodles to wok and cook 1 min. Then add yakisoba sauce. Cook 2 minutes. Add tofu and scallions. Toss to combine. Serve immediately, and enjoy!