PREPARATION:

1. Heat the olive oil and oregano in a small saucepan and heat over low heat until fragrant, about 5 minutes. Set aside to cool.
2. Place the red wine vinegar, 1 teaspoon of the salt, and 1/2 teaspoon of the pepper in a medium nonreactive mixing bowl. While whisking, add the oregano-oil in a slow, steady stream until vinaigrette is completely emulsified.
3. Gently fold 4 or 5 cucumber ribbons several times back and forth to form a squiggly pattern. Place the folded ribbons onto a large plate in a circle. Take 3 of the larger slices of tomato and stack on top of the cucumber ribbons. Season the tomatoes lightly with salt and pepper. Gently fold another 3 or 4 cucumber ribbons and lay the squiggly slices over the tomato slices. Top again with tomato slices, this time choosing the smaller slices, and season lightly with salt and pepper. Arrange one-quarter of the baby greens over the top of the stacked cucumber and tomatoes. Repeat with remaining tomato slices, cucumber slices, and greens to form the 3 remaining salads.
4. Take the red onion slices and ?hang? on the sides of the stacked salads as desired. Crumble 3 tablespoons of the feta over the top of each salad. Arrange the Kalamata olives around the salad on the plates, about 1/3 cup for each salad, then drizzle each salad with about 1/4 cup of the vinaigrette, or to taste.