Heat a wok over high heat until hot. Add 1 tbsp oil. Add spring onion, garlic, carrot, and Chinese leaf. Stir-fry for 2 to 3 minutes until soft. Add water chestnuts, bamboo shoots, bean sprouts, soy sauce, pinch of salt and pepper, stir fry for a further minute, turn off heat and add sesame oil. Transfer to a bowl and allow to cool.
Place wrapper on a board with a corner pointing towards you, brush edges with corn flour and egg mixture. Spoon a good tablespoon of vegetable mixture into corner of wrapper. Fold tip of corner over the filling creating an 8cm sausage shape, turn in other two corners to enclose filling and continue to roll. Repeat with remaining wrappers.
Pour enough oil into a wok so once spring rolls are added they can float, heat to 160c and cook the spring rolls in batches of 4, for 3 to 4 minutes or until golden brown. Remove to a wire rack or a plate lined with kitchen paper. Once all of the spring rolls are cooked, serve hot with sweet chilli sauce.