- 2 oranges, peel and pith removed
- 1 tablespoon white-wine vinegar
- 1 tablespoon Dijon mustard
- 3 tablespoons extra-virgin olive oil
- Coarse salt and ground pepper
- 1 large fennel bulb, cored and very thinly sliced, fronds reserved
- 5 ounces baby arugula (5 cups)
- Working over a medium bowl, cut out orange segments, then squeeze juice from membranes. To a jar, add 2 tablespoons juice, vinegar, mustard, and oil; season with salt and pepper. Shake to combine.
- Combine fennel and fronds, arugula, and orange segments in a bowl. Drizzle with dressing and toss to combine.
Make dressing in a small airtight jar up to a day ahead, then shake to combine and pour on salad to serve.