Freeze the pork tenderloin for about 30 minutes. Slice into very thin strips. Refrigerate.
Put the tree ear mushrooms in a small bowl and the shiitake in another. Pour boiling water over each and set aside to re-hydrate for about 30 minutes.
Meanwhile, combine the broth, garlic, and ginger in a large saucepan. Crush the white part of 1 scallion with the side of a knife. Add to the pan, cover and simmer for 15 minutes.
Thinly slice the remaining scallions and reserve. Remove the mushrooms from the water and discard the liquid. Squeeze excess moisture from the shiitake mushrooms and thinly slice.
Remove the garlic, ginger, and scallions from the broth and discard. Add the mushrooms, soy, vinegar, pepper, and salt and bring to a simmer.
Whisk in the cornstartch mixture, bring to a boil, and then simmer over medium heat for 5 minutes.
Pour the egg into the soup and stir once to make delicate threads.
Stir in the remaining scallions, oil, tofu, and pork. Return to a simmer.
Remove from heat to prevent meat from getting tough.
Adjust seasonings to taste. Serve immediately.