Cut all the vegetables into medium-sized cubes. Cut the onions into slices and mix all in a salad bowl. Add the olives and toss. Now add all the dressing ingredients except the Feta cheese and give it a good toss.
Break your feta cheese in to big chunks and place them over the salad. Sprinkle the oregano as well as a few drops of olive oil across the feta cheese and salad.