For the Vinaigrette, mix oil, lemon juice, vinegar and seasonings in small bowl with wire whisk until well blended. Stir in feta cheese. Set aside.
For the Salad, trim squash ends. Slice into ribbons with vegetable peeler or mandoline, discarding outside ribbons and core.
To serve, place squash ribbons on each salad plate. Top with tomatoes, onion and olives. Serve with Vinaigrette on the side.