Step 1: In a large skillet or wok, heat 1 tablespoon of vegetable oil over medium-high heat. Add the ground pork and cook, breaking it up with a spoon, until thoroughly browned and no pink remains. Drain any excess grease and set the pork aside.
Step 2: To the same skillet, add the minced garlic and grated ginger. Sauté for about 1 minute until fragrant.
Step 3: Add the shredded cabbage and carrots to the skillet. Cook, stirring frequently, until the vegetables soften but still retain a slight crunch, about 5-7 minutes.
Step 4: Return the cooked pork to the skillet. Stir in the soy sauce, oyster sauce (if using), sesame oil, and black pepper. Mix everything well to combine. Remove the filling from heat and allow it to cool completely before proceeding (this is crucial for preventing soggy wrappers).
Step 5: Set up your wrapping station: Place an egg roll wrapper on a clean, dry surface with one corner pointing towards you (diamond shape). Place about 2 tablespoons of the cooled filling just below the center of the wrapper, forming a log shape.
Step 6: Fold the bottom corner of the wrapper up over the filling, tucking it in snugly. Then, fold in the left and right corners towards the center, creating an envelope shape.
Step 7: Starting from the bottom, roll the egg roll wrapper upwards, keeping it as tight as possible. Before you reach the top corner, dip your finger in a small bowl of water (or use the beaten egg) and moisten the top corner. Continue rolling to seal the egg roll completely.
Step 8: In a deep pot or Dutch oven, heat 4-6 cups of vegetable oil to 350°F (175°C). Use a thermometer to maintain this temperature consistently.
Step 9: Carefully place 3-4 egg rolls into the hot oil, ensuring not to overcrowd the pot. Fry for 5-7 minutes, turning occasionally, until they are golden brown and crispy on all sides.
Step 10: Using tongs, carefully remove the fried egg rolls and place them on a wire rack set over a baking sheet lined with paper towels to drain any excess oil. Repeat with the remaining egg rolls.
Step 11: Allow the egg rolls to cool for a few minutes before serving hot with your favorite dipping sauces.