Preheat an oven to 450 degrees F. Lightly oil a large baking dish.
Peel and slice potatoes into wedges. Place the wedges into a large bowl of ice water as you complete each potato.
Drain the potatoes from the water and stir in garlic, olive oil, water, lemon juice, oregano, salt, and pepper together in a bowl until the potatoes are evenly coated; pour into the prepared baking dish.
Roast in the preheated oven until the potatoes begin to brown, about 20 minutes. Stir the potatoes. Return to the oven and bake about 20 minutes more, or until the potatoes look crispy enough.
Top with the crumbled feta cheese to serve.