For the Fries:

1. Preheat the oven to 450°F. Line a rimmed half-size baking sheet with aluminum foil or a silicone mat.
2. Peel the parsnips, trim the ends, and cut into strips about 3 inches long and 1/4 inch wide.
3. Place the parsnips in a large mixing bowl and toss with the olive oil. Add the salt, pepper, and garlic powder and toss again to coat evenly.
4. Arrange the strips in a single layer on the prepared baking sheet, making sure they don’t touch each other.
5. Transfer the baking sheet to the oven. Roast the parsnips for about 20 minutes, or until tender in the center and browned and crispy on the edges, tossing the strips and rotating the pan halfway through.
6. Remove from the oven, sprinkle with chopped parsley, and serve immediately with the dipping sauce.

For the Dipping Sauce:

1. In a small mixing bowl, whisk together the mayonnaise, mustard, honey, vinegar, salt, and cayenne (if using) until completely combined.
2. Use immediately, or store covered in the refrigerator for up to 5 days.