Heat a wok over high heat and then add one tablespoon of groundnut oil. When the oil is smoking, add the cubed chicken breast and stir-fry for 2-3 minutes until the chicken is cooked through. Add the Chinese five-spice powder, light soy sauce, and oyster sauce (if using) and stir through to coat the chicken. Transfer that cooked chicken to a plate and leave to cool.

Meanwhile, place the dried mushrooms into a small bowl and add some warm water. Leave to soak for as long as the package instructs (typically 20-60 minutes), then drain well, then cut into thin slices.

Place the cooked and cooled chicken into a large bowl with the sliced, rehydrated mushrooms, chopped garlic, grated ginger, carrot strips, bean sprouts, and finely chopped spring onions. Toss to combine and set aside.

Mix the cornflour and water together to use as a "glue" around the wrapper edges to hold them together and to stop them from bursting whilst deep frying. Set aside.

Place two spring roll sheets on top of each other onto a flat surface, with one corner facing you. Add a spoonful of the filling to this bottom end,
Fold the wrapper over the filling, then bring the sides over and continue rolling and sticking together with the cornflour/water mix to form a cigar shape. Ensure to keep the wrapping tight. Continue with the remaining wrappers and filling.

Pour the groundnut oil into a deep saucepan (or use your deep-fat fryer) and heat to 180°/350°F.

Place a spring roll onto a slotted spoon or spider strainer and lower it into the hot oil. Depending on the size of your pan, cook 1-3 at a time; do not overcrowd the pan. Cook for 3-5 minutes until crispy and golden brown. Transfer to a plate lined with kitchen paper towels to absorb excess oil. Cook the remaining spring rolls. Serve hot with a dipping sauce of choice.