Cut ½ pound firm tofu into bite-size pieces.Cut 1 small onion in half, then into not-too-thin slices.Grate 2 cloves garlic and 1 inch ginger.Cut 1 carrot into thin matches.Cut 1 heaping cup (5 oz) bell peppers into sticks or squares.Cut 1 heaping cup (5 oz) mushrooms into ¼ inch (½ cm) slices.Separate leaves of 1 heaping cup (5 oz) bok choy or chop them into bite-size chunks.Thinly slice 2 scallions ,the green and light-green tops.
Make the stir fry sauce by whisking together: 2 tablespoons dark soy sauce, 2 tablespoons vegetarian oyster sauce, 2 tablespoons rice vinegar, 1 tablespoon mirin, 1 tablespoon brown sugar, 1 teaspoon sriracha sauce.
Boil 14 ounces udon noodles in water for 1 to 2 minutes, then drain them and rinse them under cold water to prevent them from overcooking.
STIR FRY TOFU AND VEGGIES
In a large nonstick pan or wok, warm 2 tablespoons vegetable oil, add the diced tofu, season it with ½ teaspoon salt, and cook it on medium heat for 5 minutes, moving it around the pan often.Add the onion, and fry it for 3 minutes, stirring often. Then add gratedgarlic and ginger, and fry for one more minute or until you smell their fragrant aroma.
Add the veggies, and cook them on medium-high heat, tossing them with the tofu for a couple of minutes or until tender-crisp.
ADD NOODLES AND SAUCE
Add the noodles and the sauce, and toss for one more minute on medium-high heat until all ingredients are fully coated in the sauce.
Taste and adjust for salt, then serve the stir-fried udon noodles in bowls.You can top them with chopped scallions, fried onions, bonito flakes (Katsuobushi), sesame seeds, chili oil, sriracha, or sesame oil.