Brown chicken in oil in a large wok over medium high heat. Add green pepper, red pepper, carrot and garlic and stir-fry for 1 to 2 minutes.
In a small bowl, combine cornflour and soy sauce and mix together; pour mixture into the frying pan, along with the pineapple and juice, vinegar, sugar and ginger. Stir together and bring to a full boil. Serve over rice.