Heat the oil in a frying pan. Add the onion and cook over low heat for 5 minutes. Add the capsicum and cook, stirring, for 4 minutes. Remove from the pan and set aside.
Fry the eggplant until lightly browned and remove from the pan. Fry the zucchini until browned and then return the onion, capsicum and eggplant to the pan. Add the tomato paste,