This recipe's technique is what the French would call "in the style of the baker's wife." It comes from the days when a tough joint of meat was cooked slowly over aromatics in the dying embers of the wood-burning bread ovens. It is a perfect and fitting component for the pot au feu, but it would also make a perfect stand-alone Sunday supper if you threw a few roots and taters into the pan during the cooking. I prefer to brine a leg before roasting it; it's not absolutely necessary, but if time allows, a two-day brine will help keep your leg of lamb moist and flavorful.
1 (4- to 5-pound) leg of lamb, untrimmed
1 cup plus 2 tablespoons kosher salt
6 sprigs fresh rosemary, stems removed
1/2 cup fresh mint
8 garlic cloves
1 tablespoon granulated sugar
1 teaspoon freshly ground pepper
1/2 cup olive oil
1/2 cup freshly squeezed lemon juice (about 3 lemons)
4 Preserved Meyer Lemons, cut in half
Two days before you plan on serving, brine the lamb:
Dissolve 1 cup salt in 1 gallon of cold water. Place the lamb in a large container and pour the brine over. The lamb should be completely submerged. If it is not, make additional brine using the same ratio of 1 cup salt to 1 gallon water. Cover the container and refrigerate for 2 days.
Preheat the oven to 500° F. Remove the meat from the brine and dry well. Cut slits through the fat, 2 inches apart, to form a crosshatch pattern, being careful not to cut into the meat.
In the bowl of a food processor fitted with the metal blade, combine the rosemary, mint, garlic, sugar, pepper, and remaining 2 tablespoons salt. Process until roughly chopped. Press this mixture into the slits cut into the leg. Place the leg of lamb in a roasting pan and roast for 20 minutes.
Turn the oven down to 225° F. Mix the lemon juice with the oil. Add the preserved lemon halves to the roasting pan and pour the lemon juice mixture over the lamb. Continue to roast for 6 to 8 hours, checking the lamb frequently after 4 hours. The lamb is done when the meat is fall-off-the-bone tender.