Rinse and halve the peppers. Remove the core and coarsely chop. Rinse the tomatoes, remove the core, and cut into wedges. Peel the cucumber and halve lengthwise. Remove the seeds, and slice. Peel the onion and cut into wedges. Separate the layers into individual slices. Mix all the prepared ingredients with the olive. Coarsely crumble the feta cheese, and gently mix into the salad.
For the vinaigrette, mix the vinegar and oil. Season to taste with salt and pepper. Drizzle the dressing over the salad, garnish with the thyme, and serve.