In a large bowl, mix the flour, 60 ml ice-cold water, egg, and salt until a sticky dough forms. Add up to 60 ml more ice water if needed to achieve the correct consistency.

Turn the dough out onto a lightly floured surface and knead for about 5 minutes, until smooth and elastic.

Let the dough rest for 30 minutes, then knead it briefly again.

Divide the dough ball in half, wrapping one half in plastic wrap to keep it from drying out.

Roll the other half of the dough on a lightly floured surface until it is about 3 mm (⅛ inch) thick or thinner.

Cut the dough into squares measuring about 9 cm (3 ½ inches) on each side.

Dust each square lightly with cornstarch and stack them to prevent sticking.

Repeat the rolling and cutting process with the remaining dough. Use the wrappers immediately or freeze them for later use.

Heat 15 ml of vegetable oil in a large skillet over medium heat.

Add the minced garlic and ginger, sauté until fragrant.

Add the ground pork or chicken and cook until browned and fully cooked.

Stir in the soy sauce, oyster sauce, and sesame oil.

Add the cabbage, carrots, and bean sprouts, and cook for 3-4 minutes until the vegetables are tender.

Mix in the chopped spring onions, then remove the filling from the heat and let it cool slightly.

Place one pastry sheet on a clean surface, with one corner pointing towards you (like a diamond).

Spoon about 2 tablespoons of the filling onto the lower third of the pastry.

Fold the bottom corner over the filling, then fold in the sides, and roll tightly towards the top corner.

Brush the top corner with the beaten egg to seal the roll.

Repeat the process with the remaining pastry sheets and filling.

Heat 500 ml of vegetable oil in a deep pot or fryer to 180°C.

Carefully fry the egg rolls in batches, turning occasionally, until they are golden brown and crispy (about 3-4 minutes per batch).

Remove the egg rolls with a slotted spoon and drain on paper towels.