Fennel-Arugula Salad with Oranges

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.