1Place sugar, vinegar, salt, soy sauce and pineapple juice in a small saucepan over a high heat. Bring to boil and then reduce to low.
2In a small glass combine cornflour with 1 tablespoon water. Stir until smooth and pour into sweet and sour sauce. Heat for a further 2 minutes or until mixture boils and thickens. Remove from heat and set aside.
3Pour peanut oil into a large wok and place over a high heat. After 30 seconds add onion, green beans, capsicum, corn and bok choy. Toss regularly cooking for 1 minute and add in the tofu and sesame oil. Toss for a further 2 minutes then pour in sweet and sour sauce. Swirl around in wok for a further 30 seconds until well combined, before transferring to a serving dish.