Step 1: In a large skillet or wok, heat 1 tablespoon of sesame oil over medium-high heat. Add the ground pork and cook, breaking it up with a spoon, until it's browned and cooked through. Drain any excess grease.
Step 2: Add the minced garlic and grated ginger to the skillet with the pork. Sauté for about 1 minute until fragrant.
Step 3: Stir in the shredded cabbage and carrots. Cook for 5-7 minutes, stirring occasionally, until the vegetables have softened but still retain a slight crispness. You don't want them mushy!
Step 4: Pour in the soy sauce, oyster sauce, and rice vinegar. Mix well to combine everything. Cook for another 2-3 minutes, allowing the flavors to meld and any excess liquid to evaporate. The filling should not be watery. Remove from heat and let the filling cool completely. This is crucial; warm filling can make your wrappers soggy.
Step 5: Lay an egg roll wrapper on a clean, dry surface with one corner pointing towards you (like a diamond). Place about 2-3 tablespoons of the cooled filling just below the center of the wrapper. Don't overfill, or they'll be hard to roll and might burst.
Step 6: Fold the bottom corner up over the filling, tucking it in tightly.
Step 7: Fold in the left and right corners towards the center, creating an envelope shape.
Step 8: Roll the wrapper tightly from the bottom upwards. Before you reach the top corner, moisten the edges of that corner with a little water (or an egg wash made from a beaten egg and a tablespoon of water) to seal it securely. This ensures your egg roll stays intact during cooking. Repeat with the remaining filling and wrappers.
Step 9: In a large, deep pot or Dutch oven, heat about 2-3 inches of vegetable oil (or another high smoke point oil like canola or peanut oil) to 350°F (175°C). Use a candy thermometer to monitor the temperature; maintaining the correct temperature is key to a crispy, non-greasy result.
Step 10: Carefully lower 3-4 egg rolls into the hot oil, ensuring not to overcrowd the pot. Fry for 4-6 minutes, turning occasionally, until they are golden brown and crispy on all sides.
Step 11: Remove the cooked egg rolls with a slotted spoon or tongs and place them on a wire rack set over a paper towel-lined baking sheet to drain excess oil. Serve immediately with your favorite dipping sauce.