3 oranges
1 tablespoon sherry wine vinegar
1/2 cup extra-virgin olive oil
2 cups mâche (loosely packed)
1 large head of frisée (halved, torn into pieces, about 6 cups, loosely packed)
1 large head of Chioggia, Tardivo, or Castelfranco radicchio (halved, torn into pieces, about 5 cups, loosely packed)
1/2 medium red onion (sliced thinly, about 2 cups)
1/2 cup Kalamata olives (pitted and halved)
4 ounces feta cheese (crumbled)
  Salt and freshly ground pepper (to taste)