A persillade is a mixture of chopped parsley - persil in French - and garlic that is added to dishes as a flavoring or garnish.

In a blender purée 2 tablespoons parsley, oil, 1 teaspoon chopped garlic, zest, and salt until parsley is finely chopped. Sauce may be make 1 day ahead and chilled, covered.

Preheat oven to 425°F.

Untie and unroll lamb. Season inside of lamb with salt and pepper and sprinkle with remaining parsley and minced garlic. Reroll lamb and retie with kitchen string. Season outside of lamb with salt and pepper. Put lamb on a rack in a roasting pan and roast in middle of oven 30 to 40 minutes, or until a meat thermometer registers 125°F. for medium-rare or 130°F. for medium. Transfer lamb to a cutting board and let stand 10 minutes.

In a small saucepan heat sauce over moderate heat until hot and just before serving stir in lemon juice. Slice lamb about 1/2 inch thick.

Divide sauce between 2 plates and top with lamb.

Serves 2 generously.