- Finely grate peel of one orange; set aside.
- Cut the same orange in half; squeeze juice into a 1-cup measuring cup.
- Add the oil, Worcestershire sauce, sugar, salt, pepper and reserved orange peel. Gradually whisk in vinegar; set aside.
- Peel and discard white membrane from remaining oranges; cut into sections.
- In a large bowl, combine the spinach, feta, dried cranberries and orange sections. Drizzle with 1/4 cup vinaigrette and toss to coat. Cover and refrigerate any remaining vinaigrette for another use.