Cut chicken into bite-sized pieces. Dice red bell pepper and onion into similar-sized pieces. Slice zucchini into 1cm thick rounds.

Mix marmalade, soy sauce, and sake in a container to prepare the sauce.

Heat olive oil in a frying pan over medium heat. Add chicken and cook until browned, then flip and cook for another 2 minutes. Add onion and red bell pepper, stir-fry until coated with oil, then cover and steam for 3 minutes.