Heat a wok until hot and add oil, add chicken and mushrooms and stir-fry for 1-2 minutes. Season with 1 tbsp soy sauce and five-spice powder, then remove from the wok and set aside to cool for ten minutes. Wipe the wok clean with kitchen paper
Place the ginger, bean sprouts, green onions, carrot and Thai basil into a bowl, add the chicken and mushrooms mixture and season with the oyster sauce, remaining soy sauce, sea salt and ground white pepper. Stir well to combine
Lay two spring roll wrappers one on top of the other (the extra thickness will prevent the skin from breaking) and position so that the corners are pointing upwards, downwards and to the sides
Place 1 wrapper on a board with a corner pointing towards you. Spoon two tablespoons of the filling into the centre of the wrapper. Brush each corner of the wrapper with a little water. Then start rolling up from the bottom. When the filling is covered, pull the corners in from each side (to seal the ends as you go). Continue rolling until the filling is tightly covered, then press to seal the top corner. Seal it with a little water and brush spring roll lightly with the egg yolk. Repeat with the remaining spring roll wrappers and filling
Heat the wok over a high heat and fill the wok to a quarter of its depth with peanut oil. Test oil with a small piece of bread - when bread bubbles and turns golden brown the oil is ready). Carefully lower the spring rolls in small batches into the oil and deep-fry for 2-3 minutes, or until golden-brown. Remove with a slotted spoon and drain on kitchen paper. Transfer the spring rolls onto a plate and serve immediately with plum sauce
Tips & Hints:
You can also use a deep fryer to prepare the spring rolls.