Combine pork and cornstarch in a bowl, stir and sprinkle with salt and pepper.
Combine garlic, mushrooms, ginger, cabbage, and scallions on a plate and set aside.
In a small bowl stir together the soy sauce, rice vinegar, oyster sauce and sesame oil.
Heat 1 t. peanut oil in a non-stick skillet.
Pour in eggs and cook without stirring for several minutes.
Place on a cutting board, roll and cut into small strips.
Wipe out skillet and add the remaining 3 t. of peanut oil.
Heat over medium heat until hot and add pork. Cook for about 4 minutes until pork is almost done. Remove pork to a plate.
Add mushrooms to the skillet and cook for about 4 minutes.
Then add pork, cabbage mixture, soy sauce mixture, and eggs and cook for 2-3 minutes until heated through.
Put moo shu pork in a bowl and top with peanuts.
Serve with warmed tortillas and hoisin sauce.