Roast lamb with potatoes feels like a New American dish, but chef Marco Mattana adds Roman flavor by including garlicky braised artichokes. Slideshow: More Lamb Recipes
Preheat the oven to 350°. Squeeze the lemon half into a bowl of cold water; add it to the water. Snap off the outer leaves of 1 artichoke. Using a sharp knife, cut off the top half and peel the base and stem. Using a melon baller or a spoon, scoop out the furry choke; halve the artichoke lengthwise and add to the lemon water. Repeat with the remaining artichokes.
Drain the artichokes; transfer to a medium saucepan. Add 1/2 cup of the oil, the garlic, mint, oregano sprigs and 1/4 cup of water; season with salt and pepper. Bring to a simmer, cover and cook over low heat until just tender, about 20 minutes. Keep warm in the saucepan.
Set a rack over a baking sheet. Heat a large cast-iron skillet. Rub the lamb all over with 2 tablespoons of the oil and season with salt and pepper. Sear 1 rack of lamb at a time over moderately high heat, turning, until golden, about 5 minutes. Transfer to the baking sheet and roast for about 30 minutes for medium-rare; an instant-read thermometer inserted in the center will register 120°. Transfer to a cutting board and let rest for 10 minutes.
Meanwhile, in a large saucepan, cover the potatoes with 2 inches of water, season with salt and bring to a boil. Cook over moderate heat until tender, about 20 minutes. Drain, reserving 1/2 cup of the cooking water. Return the potatoes to the saucepan and add the remaining 1/2 cup of oil and 1/4 cup of the reserved cooking water. Season with salt and coarsely mash with a fork; add more cooking water if necessary. Stir in the licorice powder, if using.
Transfer the artichokes to 6 plates. Carve the lamb into individual chops and serve with the artichokes and crushed purple potatoes. Garnish with oregano leaves.
The artichokes and crushed potatoes can be refrigerated separately overnight and reheated before serving.
Rich and smoky red.