Garlic Rosemary Roasted Boneless Leg of Lamb

Boneless leg of lamb

This low and slow method of roasting provides an evenly cooked and juicy roast. I found that 25 minutes per pound worked well at the 275 degrees F. My four-pound roast was medium rare (135 degrees F) after 1 hour 20 minutes. I had left the roast on the kitchen counter for 2 hours before roasting.




  1. Line a 15-by-10-by-1-inch baking sheet with foil.
  2. Combine the oil, mustard, rosemary and garlic in a small bowl.
  3. Roll and tie the roast with butcher twine, or ask your butcher to do it for you.
  4. Generously season the roast all over with salt and pepper.
  5. Heat a skillet large enough to hold the roast over medium-high heat. Pour in the oil and swirl across the bottom. Lay the fatty side of the lamb on the bottom of the pan and sear for 3 minutes.
  6. Turn one quarter and sear 3 minutes, repeat 2 more times with a quarter turn each.
  7. Place a good dollop of the marinade on the lined baking sheet and then place the lamb, fatty side up, on the marinade. Scoop the remaining marinade on top of the roast and spread all over the remaining 3 sides.
  8. Cover and refrigerate at least 4 hours, preferably overnight.
  9. Bring the lamb out of the refrigerator about 2 hours before roasting. Preheat the oven to 275 degrees F about 15 minutes before cooking.
  10. Place in the oven and roast for 1 1/2 hours for medium rare. Use a thermometer to check internal temps.
  11. Let rest for 10-20 minutes. Tent with foil if the weather is cool.
  12. Slice, place on a warm platter and garnish with rosemary sprigs.