This is one of my favorite egg tofu dishes from Chinese restaurants. The secret is to deep-fry the tofu to develop a brown skin on them. Not only is it flavorful, but it protects the tofu from falling apart in the sauce.
Soak the shiitake mushrooms in 2 cups of water in the fridge overnight. If you are short on time, you can simmer them in a small pot for 20 minutes instead. Once they are rehydrated, cut off and discard the stems.
Cut through the dotted line on the egg tofu package and squeeze one end of the package to push out the tofu. Cut the tofu into 1 ½-inch thick cylinders. Repeat with the other package.
Heat about 1 inch of oil to 375-400°F (the oil MUST be this hot for the skin to form on the tofu). Use a metal spider and gently lower 5-6 pieces of tofu into the hot oil. Cook the tofu for 2-3 minutes until a brown skin forms around them. Remove to a paper towel-lined plate to dry. Wait for the oil to reheat before frying the rest of the tofu.
Heat a pot of boiling water and blanch the bok choy for 45 seconds. Drain and set the bok choy aside.
Heat one tablespoon of oil in a wok over medium heat. Add the garlic and ginger and cook for 20 seconds. Add mushroom-soaking water, then add the oyster sauce, soy sauce, dark soy sauce, and sugar, and bring to a boil.
Combine the cornstarch with 2 tablespoons of water, then stir it into the sauce to thicken.
Add the bok choy, shiitake mushrooms, and egg tofu and gently stir to coat everything in the sauce. If you prefer the sauce more runny, you can add a little more water. Enjoy!
Notes
Sometimes, I will also add a handful of dried scallops to the container of soaking shiitake mushrooms.