Gerard Craft recommends seasoning lamb with salt and pepper, covering it with plastic wrap and letting it sit overnight in the refrigerator; simpler than brining, this method helps keep the meat succulent.
Season the lamb roasts generously with salt and pepper, wrap in plastic and refrigerate overnight. Bring the roasts to room temperature before cooking.
Preheat the oven to 325°. In a food processor, pulse the almonds with the garlic until finely chopped. Add the mint leaves, cheese and 3/4 cup of the oil and process until smooth. Season the pesto with salt.
In a large skillet, heat the remaining 2 tablespoons of olive oil until shimmering. Add the roasts and cook over high heat, turning, until browned all over, about 10 minutes. Transfer the roasts to a large roasting pan and spread half of the pesto over them. Cover tightly with foil and roast for about 2 hours, until an instant-read thermometer inserted in the center of each roast registers 170°. Remove the foil, increase the oven temperature to 425° and roast for 30 minutes longer, until browned on top. Transfer the lamb to a cutting board and let rest for 10 minutes.
Remove the strings and carve each roast into 1/2-inch-thick slices. Serve with the remaining pesto and lemon wedges.