Scatter the tomatoes, green peppers and onion in a shallow ovenproof dish.
Mix the garlic with the oregano, oil, plenty of pepper and a little salt. Drizzle the mixture over the vegetables. Bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 10 minutes.
Crumble the feta into small pieces and scatter over the vegetables along with the olives. Return the dish to the oven for a further 15 minutes. Serve warm with toasted pitta breads.