Put the potatoes in a large pot of cold, well-salted water to cover. Bring to a boil and cook until a knife slips in easily. 15 to 20 minutes. Drain the potatoes. When they are cool enough to handle, hold one between your hands as if you were clapping and press gently with the heel of one hand. You want to smash the potato to about a ½-inch thickness while keeping it in one piece. The skin will split, but the potato should not fall apart. Repeat with the remaining potatoes. You can prepare the potatoes to this point several hours ahead.

Pour ½ inch of peanut oil in a large skillet and heat over moderately high heat.

When the oil begins to smoke, carefully put the smashed potatoes in the oil and cook on both sides until crisp and well browned, 8 to 10 minutes. With a slotted spoon, transfer to paper towels to drain. Season with salt and pepper.

While the potatoes cook, combine the parsley and lemon zest in a serving bowl. Heat the olive oil in a small skillet over moderately high heat. Add the garlic and sauté until lightly browned. With a slotted spoon, transfer the garlic to the bowl with the parsley-lemon mixture.

When the potatoes are ready, add them to the garlic mixture and toss gently. Serve immediately. Save the leftover garlic oil and use it to dress a salad or vegetables the following day.