In a large bowl, whisk together the olive oil and lemon juice and a sprinkle of salt and pepper. Add the thinly sliced red onions and let them pickle a bit, while you prepare the rest of the veggies.
Add the rest of the vegetables and the cheese to the bowl. Toss to combine and season with more salt and pepper if needed.
Top with the crumbled dried oregano for serving.
Notes
Can sub red wine vinegar for the lemon juice. Can leave out lemon juice and/or vinegar and just serve dressed in olive oil. You want a good fruity olive oil for this.