Heat oil in a frypan over medium-high heat. Cook onion, stirring, for 3-4 minutes until softened. Increase heat to high, add pork and cook, stirring, for 8-10 minutes until golden. Add garlic, ginger, char siu sauce and five spice, and cook for 2 minutes or until fragrant. Add the rice wine and cook for 3-4 minutes until caramelised.