Make the filling: Heat the vegetable oil in a skillet over medium heat. Add the garlic and sauté until fragrant and golden. Add the shiitake mushrooms and cook until aromatic. Add the ground pork and cook until no longer pink. Add the cabbage, bean sprouts, carrots, glass noodles, and water. Stir-fry until cooked. Season with soy sauce, salt, and sugar, mixing well. Taste and adjust for a lightly salty flavor. Add the black pepper and stir to combine.

To assemble: Place a spring roll wrapper on a flat surface. Add some filling, then roll up tightly into a log, folding in the sides as you go. Seal the edge with the flour paste or egg white.

Heat oil in a skillet over medium heat. Fry the spring rolls in batches, turning occasionally, until golden brown all over. Remove and drain on paper towels.