Slice 4 peeled potatoes into 1 1/2-inch rounds. Toss in an ovenproof skillet with 1/3 cup lemon juice, 1/4 cup olive oil, 4 smashed garlic cloves, 4 oregano sprigs, and salt and pepper. Add enough water to come halfway up the sides of the potatoes. Cover, bring to a boil and cook 5 minutes. Uncover and roast at 500 degrees F, 30 more minutes.