How to Make It
Place a rimmed baking sheet in oven; preheat oven to 500°F. (Do not remove pan while oven preheats.)
Combine parsnips, walnuts, thyme, maple syrup, salt, and pepper. Arrange in a single layer on preheated baking sheet. Bake in preheated oven until tender, about 10 minutes. Toss with vinegar.