Liberally coat entire leg with sea salt and pepper. Place in plastic bag and refrigerate for 2 hours but up to 24. The longer you wait, the more the salt will penetrate the meat and season it throughout.
Remove lamb from bag and rinse with cool water and pat dry.
Preheat oven to 425° F
While oven is preheating use a pairing knife to cut slits about 1 inch deep all around the lamb. Stuff garlic clove slices and rosemary sprig pieces in each slit.
Place lamb in a roasting pan and roast in oven at 425° F for 30 minutes to get an 'oven sear'
Reduce heat to 325° F and roast leg of lamb until internal temperature reads 132°-135° on an oven thermometer.
Once desired doneness has been achieved, remove lamb from oven and let rest at MINIMUM of 30 minutes but ideally up to an hour. This will allow the juices to relax inside the lamb and keep it moist.
Slice lamb perpendicular to the bone and serve.
Enjoy!
Recipe by Pastured Kitchen at https://www.pasturedkitchen.com/recipes/roasted-leg-of-lamb/