In a small bowl, mix the cornflour and water to create a paste for sealing the rolls.
Carefully separate one spring roll wrapper, keeping the others covered with a damp tea towel to prevent drying. Lay the wrapper on a flat surface with the smooth side facing down, positioned like a diamond. Place a generously heaped dessert spoonful of filling near the bottom. Begin rolling tightly halfway, fold in the sides, then continue rolling to the top. Use the cornflour paste to seal the edges. The final rolls should measure approximately 12 cm / 5” in length and 2.5 cm / 1” in width.
Heat enough oil in a wok or deep saucepan so that the spring rolls are fully submerged when frying. Heat the oil over medium-high heat until hot—test by dipping a bamboo chopstick or wooden spoon handle in; if bubbles form rapidly, the oil is ready.
Carefully lower the spring rolls into the hot oil, cooking 4 to 5 at a time. Fry, turning occasionally, until they achieve a deep golden color, which takes around 1 1/2 to 2 minutes. Transfer to paper towels to drain excess oil.
Repeat the process with the remaining spring rolls. Serve them hot, paired with the Sweet and Sour Sauce.