Fried Spring Rolls

Name: Fried Spring Rolls
Ingredients: 8 dried shiitake mushrooms; 1 pound pork loin or tenderloin; 1 tablespoon cornstarch; 1 1/2 teaspoons sugar; 1 tablespoon sesame oil; 1 1/2 teaspoons Shaoxing rice wine , optional; 4 teaspoons soy sauce; 1/2 medium head napa cabbage , thinly sliced (about 6 cups); 3 medium carrots , julienned; 1/2 teaspoon kosher salt; 3 scallions , thinly sliced on a bias; 2 teaspoons ginger, minced; 4 cups canola or vegetable oil , divided; 3 tablespoons oyster sauce; 1 large egg; 50 to 60 (6-inch) square spring roll wrappers; Chinkiang vinegar or black vinegar, to serve