Rinse the cucumber and cut into slices. Rinse the peppers, pat dry, remove seeds and ribs and cut into narrow strips. Rinse the tomatoes, remove the cores and cut into eighths.
Peel the onion and cut into rings. Combine the vegetables, olives and the diced cheese on a plate, drizzle with oil, season with salt and pepper and serve sprinkled with oregano. Serve with toasted white bread.