General tips
Bone-in leg is the move, not boneless. The bone marrow seeps flavor into the surrounding meat during the long bath, and the bone itself helps the meat keep its shape. Boneless leg comes pre-tied in netting that traps weird textures and uneven cooking.
Salt 24 h ahead. Lamb leg is lean and dense, and salt needs the full day to penetrate the muscle and pull out moisture, then redistribute it. This is dry brining, and it transforms a good lamb leg into a great one. No skipping.
Cook at 135°F for 6–8 h for medium-rare with full collagen breakdown. Going lower keeps the meat steakier; going higher gives you a more sliceable, traditional roast texture. The 135°F mark is the modern sweet spot.
Sear hot and fast at the end. After the bath, pat the leg completely dry, then sear in a screaming hot cast iron skillet (or under a broiler) for 2–3 min per side. You want a deeply browned crust without giving the interior any more time to cook.
Anti-tip: don't carve the lamb leg with the grain. Lamb's grain runs along the length of the leg. Cut against it (across the leg) for tender slices. Cutting with the grain gives you long, chewy strands that taste tough no matter how perfectly you cooked it.
Medium-Rare tips
Score the fat cap before seasoning for better flavor penetration
Use fresh herbs for brightest flavor
Rest after searing before carving for juiciest results
Medium tips
This temperature is forgiving and holds well
Great for beginners new to cooking lamb
Add fresh herbs after searing for brightness