01 - Prepare all vegetables by shredding cabbage, julienning carrots, slicing mushrooms and scallions. If using protein, cook and chop finely.
02 - Heat a large skillet or wok over medium-high heat. Add 1 teaspoon vegetable oil, then sauté minced garlic and ginger until fragrant, about 30 seconds.
03 - Add cabbage, carrots, mushrooms, and scallions to the skillet. Stir-fry for 2-3 minutes until just softened but still crisp.
04 - Add bean sprouts, soy sauce, sesame oil, oyster sauce, and white pepper. Stir-fry for 1-2 minutes more until everything is well combined and coated.
05 - Stir in optional protein if using. Transfer filling to a baking sheet or tray to cool completely before wrapping.
06 - Place a spring roll wrapper on a clean surface with a corner facing you. Spoon 2 tablespoons filling near the bottom corner. Fold the bottom corner over the filling, fold in the sides, and roll tightly. Seal the edge with cornstarch slurry.
07 - Heat 2 inches of vegetable oil in a deep pan to 350°F.
08 - Fry rolls in batches without overcrowding, turning occasionally, until golden brown and crispy, about 3-4 minutes. Drain on paper towels.
09 - Serve immediately with sweet chili sauce, soy sauce, or your favorite dipping sauce.