Preheat the oven to 425° F/220° C. Arrange the potatoes on the roasting pan and bake until tender when pierced with a fork, about 25 to 30 minutes.
While the potatoes bake, put the Vidalia onion wedges in the food processor and process until the onion is minced and juicy, about 15 to 20 seconds. Add the apple cider vinegar, honey, Dijon mustard, sea salt, and pepper. Process until all the ingredients are thoroughly mixed together, about 10 seconds. While running the processor, drizzle in the olive oil until it is fully suspended, about 5 to 8 seconds. Pour into a pint jar.
Remove the potatoes from the oven and allow to cool in the pan until they are warm but not burning your fingers, about 5 to 10 minutes. Quarter the potatoes and put the pieces in a serving bowl. Toss about 1/2 cup (120 ml) of the vinaigrette with the potatoes, adding more vinaigrette to taste. Toss in the parsley and serve. The remaining vinaigrette can be used for other salads and will keep in the refrigerator up to two weeks.