Cut the tomatoes into cubes. Wash and peel the cucumbers, cut lengthwise, then crosswise into pieces. Cut the bell pepper into cubes, removing the seeds.
In a salad bowl arrange the tomatoes, then the cucumbers and bell pepper. On top place thinly sliced onion. Season the vegetables with salt and pepper, drizzle with olive oil mixed with lemon juice.
Grate the cheese and sprinkle over the salad. Add chopped parsley and garnish with black olives.