Begin by filling a large pot with water and adding a generous amount of salt. Bring to a rolling boil and add potato wedges. Cook for about 10 minutes until tender but firm. Drain and cool.

In a mixing bowl, combine garlic powder, onion powder, lemon zest, lemon juice, extra-virgin olive oil, kosher salt, freshly ground black pepper, and rosemary. Whisk until blended. Reserve a small portion for garnish.

Preheat the grill to medium-high heat (around 400°F) and oil the grates to prevent sticking.

In a large bowl, toss the cooled boiled potatoes with the marinade, ensuring each wedge is coated. Allow them to marinate for 5-10 minutes.

Arrange the marinated potatoes on the grill in a single layer. Grill for about 20 minutes, turning every 5 minutes until golden brown and crispy.

Remove from the grill, toss with reserved marinade and parsley. Serve hot.