Preheat the oven to 375 degrees F.

Bake the sweet potatoes until they can be just pierced with a knife, about 45 minutes.

Cut the baked sweet potatoes into large chunks.

Preheat a grill to high heat.

Brush the sweet potatoes and scallions with 1/3 cup olive oil.

Arrange the potatoes and scallions on the grill.

Grill the potatoes until just tender, about 5 minutes per side.

Grill the scallions until softened and marked, about 1 minute per side.

Remove the scallions and potatoes from the grill.

Cut the grilled scallions into small pieces.

In a large bowl, whisk together the remaining 1/3 cup olive oil, dijon mustard, apple cider vinegar, balsamic vinegar, and honey.

Season the vinaigrette with kosher salt and freshly ground pepper to taste.

Add the grilled potatoes, grilled scallions, and fresh parsley to the bowl with the vinaigrette.

Toss until the potatoes are well coated with the dressing.

Serve immediately or at room temperature.