Preheat the oven to 375°F (190°C). Take the lamb out of the fridge and let it sit at room temperature for 30-60 minutes.
Mix the herb rub ingredients in a small bowl to form a paste.
Pat dry the lamb with paper towels. Make shallow cuts (about ½ inch deep) all over the lamb with a sharp knife.
Rub the herb mixture over the lamb, pressing it into the cuts. Place the lamb on a roasting rack in a large roasting pan.
Roast uncovered for 1 hour 40 minutes to 2 hours 30 minutes, until the internal temperature reaches 130°F (55°C) for medium-rare, 140°F (60°C) for medium or 150°F (65°C) for medium well. Use a meat thermometer for accuracy.
Remove from the oven and tent loosely with foil. Let rest for 15-20 minutes.
Slice the lamb thinly and arrange on a platter. Garnish with lemon slices and fresh herbs.