How to Make It
Bring a saucepan of water to a boil. Add the udon and cook until tender, 5 minutes; drain. Toss with 1 teaspoon of the canola oil.
Meanwhile, put the panko in a large, resealable plastic bag and crush into fine crumbs. In a shallow bowl, gently toss the tofu with the egg yolk. Transfer the tofu to the bag and coat with the panko.
Heat the remaining 1/2 cup of oil in a wok until just smoking. Add the tofu and stir-fry over high heat until crisp, 2 to 3 minutes. Using a slotted spoon, transfer to a paper towel-lined plate.
Pour off all but 1/4 cup of the oil and return the wok to high heat. Add the mushrooms and stir-fry until lightly browned, about 3 minutes. Add the ginger, garlic and bok choy and stir-fry for 5 minutes. Add the udon and oyster and hoisin sauces and stir-fry for 2 minutes. Add the tofu and toss. Transfer to a bowl and serve.