Preheat oven to 400°F.
Toss potatoes with olive oil, rosemary, lemon juice, salt, pepper, and garlic powder.
Place potatoes cut-side down on a sheet pan.
Roast 45 minutes until golden.
Flip and roast another 15 minutes until tender and crispy.
Finish with lemon zest, parsley, and flaky sea salt before serving.