Zest and juice of 1 lemon
Preheat oven to 450° F. Heat an oven proof skillet large enough to hold both racks of lamb until hot over medium-high heat. If you do not have a skillet large enough for both racks then place a roasting pan in the oven to heat up as the oven does.
Season the lamb generously with salt and pepper on both sides. Heat one tablespoon of oil in the pan and sear the lamb on all sides for about 2 minutes per side. Let the lamb cool a little.
Put the pistachios in the bowl of a food processor and pulse a few times to grind them. Add the remaining 2 tablespoons of olive oil, the mint, garlic, zest and juice of lemon. Process until it turns into a paste. Spread the paste on the meat-side of the lamb racks pressing down firmly. Place the lamb racks back into the skillet (or roasting pan) bone-side down. Roast for 20 minutes for medium rare, 25 minutes for medium. Cover the lamb with foil and let sit for 10 minutes before cutting the lamb into chops, use a sharp, thin knife to carve.