Preheat the oven to 425 degrees F.On a large baking sheet, toss together the potatoes, lemon, 1 tablespoon olive oil and a small pinch of salt. Transfer to the oven and roast 20 minutes or until the potatoes are fork tender. Remove the lemon from the pan and then use the back of a spatula or a fork to gently press down on the potatoes, smashing them to about 1/4 inch thickness.In a small bowl combine 2 tablespoons olive oil, the garlic and oregano. Spoon the mix evenly over the smashed potatoes. Season with salt and pepper. Sprinkle with parmesan. Return the potatoes to the oven and roast another 20-25 minutes or until golden and crisp. Meanwhile, finely chop the roasted lemon (peel and all) and add to a small bowl along with the remaining 2 tablespoons olive oil, the basil, and a pinch of salt. Drizzle the potatoes with lemon mixture and serve with feta. Eat!