Zest the oranges and set the zest aside. Cut the oranges in half and juice them directly into a blender–you should have about 1/3 cup of juice.
Add the vinegar, honey, mustard, salt, and pepper to the jar of the blender. While the blender is running on low speed, add the oil in a slow, steady stream.
Transfer to a storage container and stir in the reserved zest. Allow to stand for at least 1 hour before serving.

This bright and citrusy dressing is perfect for drizzling over salads, grain bowls, and roasted vegetables or as a marinade for grilled chicken, scallops, steak, or tofu.