Preheat oven to 400°F (200°C). Peel potatoes and cut into large wedges, about 1 to 1.5 inches at the widest point.
In a large bowl, whisk together olive oil, lemon juice, garlic, oregano, salt, pepper, and lemon zest. Add potato wedges and toss to coat thoroughly.
Transfer potatoes and liquid to a large roasting pan. Arrange in a single layer, cut side down. Pour hot water into the pan — liquid should reach halfway up the potatoes.
Roast for 40 minutes without opening the oven door.
Remove pan, flip each potato wedge. If liquid has fully evaporated, add 1/4 cup hot water. Return to oven.
Roast for another 25-35 minutes until liquid is absorbed, edges are deep golden brown, and a fork slides easily into the center of a wedge.
Rest 5 minutes, then transfer to a serving platter. Finish with flaky sea salt and serve with lemon wedges.