I have worked with this recipe until it's "just right" for my family. It's so easy, ALWAYS a hit AND it's healthy! It can also be prepared it on the grill with equally good results (keep an especially close eye on the temperature of the meat if you grill it). Don't forget the Yogurt Mint Sauce! It's the perfect finishing touch.
Place the chopped lemon, rosemary, garlic and olive oil in a food processor until finely chopped. If you don't have a food processor, finely chop all ingredients together by hand.
Rinse lamb and pat dry. Butterfly and lay flat.
Here's a great video on out to butterfly your leg of lamb. It doesn't need to look perfect! It just needs to be reasonably flat.
Rub both sides of the lamb with the salt and pepper.
Spread and massage the lemon paste evenly over the inside and outside of the lamb. Place in in a large resealable plastic bag. Refrigerate overnight to marinate, turning and massaging occasionally.
Remove lamb from refrigerator 45 minutes to one hour prior to cooking. Preheat the oven to 450 degrees. Place the lamb on a rack in a foil-lined roasting pan or rimmed baking sheet.
Place the meat in middle of the oven. After 5 minutes, reduce the temperature to 425 degrees. Roast for 25-40 minutes, or until medium rare, 140 degrees on an instant read thermometer. Begin checking temp after 25 minutes.
Remove and tent loosely with foil. Allow the meat to rest for 10 to 15 minutes before carving and serving.