Shred the cabbage finely and place it in a large bowl. Grate the carrot and add to the bowl. Sprinkle 1/2 teaspoon salt over the shredded cabbage and carrot, toss, and let sit 5 minutes to draw out excess moisture. After 5 minutes, squeeze the cabbage and carrot firmly in a clean towel or between hands to remove as much liquid as possible; discard the liquid.

Cook pork and aromatics

Heat a nonstick skillet over medium-high heat and add 1 teaspoon neutral oil (from the cooking oil). Add the ground pork and cook, breaking up with a spatula, until no longer pink and starting to brown, about 4–5 minutes. Push the meat to the side and add the minced garlic and grated ginger; cook 30 seconds until fragrant. Mix together with the meat.

Season & bind

Stir in the squeezed cabbage and carrot, sliced green onions, 2 tablespoons soy sauce, 1 tablespoon oyster sauce (if using), 1 teaspoon sesame oil, 1 teaspoon rice wine (if using), 1 teaspoon cornstarch, 1/2 teaspoon salt, and 1/4 teaspoon black pepper. Cook, stirring, until excess moisture mostly evaporates and filling is cohesive, about 2–3 minutes. Taste and adjust seasoning as needed. Remove from heat and let the filling cool for 10 minutes (this prevents soggy wrappers).

Wrappers & Seal

Make flour slurry

Whisk together 1 tablespoon all-purpose flour with 2 tablespoons water until smooth to make a sealing slurry. Set aside.

Assemble egg rolls

Lay one egg roll wrapper on a clean work surface in a diamond orientation (one corner pointing toward you). Spoon about 3 to 4 tablespoons of cooled filling onto the lower third of the wrapper, forming a log about 1" wide. Fold the bottom corner up over the filling, tuck tightly, then fold the left and right corners toward the center. Brush the top corner edge with the flour slurry and roll tightly to seal. Repeat with remaining wrappers and filling. You should make 4 egg rolls; if extra filling remains, store or pan-fry as desired.

Cooking

Heat oil

Pour about 1/2 to 1 inch of neutral oil into a heavy skillet or wok (about 2 cups listed as total; adjust to pan). Heat the oil over medium-high until it reaches 350°F (175°C) or a piece of wrapper dropped in sizzles and browns in about 20–30 seconds.

Fry egg rolls

Working in a single layer (do not overcrowd), carefully add egg rolls seam-side down to the hot oil. Fry, turning occasionally, until evenly golden brown and crisp on all sides, about 3–4 minutes per roll depending on size and oil temperature. Use tongs to roll them for even color.

Drain and rest

Remove cooked egg rolls to a wire rack set over a baking sheet or paper towels to drain briefly. Let rest 2–3 minutes so the filling finishes cooking and the wrapper crisps.

Optional Dipping Sauce

Mix sauce

Whisk together 2 tablespoons rice vinegar, 1 tablespoon soy sauce, 1 teaspoon sugar or honey, 1/2 teaspoon chili flakes or a small dash of sriracha, and 1/2 teaspoon sesame seeds if using. Taste and adjust sweet, salty, or spicy elements to preference. Serve alongside hot egg rolls.