How to Make It
Heat 1 tablespoon of the olive oil in a large, enameled cast-iron casserole. Add the bacon and cook over moderately high heat until golden and crisp, about 5 minutes. Add the onion and the 4 whole garlic cloves and cook until softened and just golden, about 5 minutes longer. Add the flageolets, parsley stems, bay leaf and thyme sprigs and toss to coat. Add the chicken stock, 3 cups of the water and 3 tablespoons of the olive oil.
2. Preheat the oven to 350°. Top the beans with crumpled, moistened parchment paper, then cover and bake for about 2 1/2 hours, stirring gently 2 or 3 times; the beans should be tender, but not mushy. Season the beans with salt and pepper. Drain the beans; reserve their cooking liquid and discard the parsley bundle, thyme, garlic cloves and bay leaf.
Using a sharp paring knife, make 1-inch incisions about 1 inch apart all over the lamb. Insert the garlic slices into the slits. Increase the oven temperature to 375°.
Set the lamb in a large roasting pan and drizzle with the lemon juice. Rub the lamb with the remaining 2 tablespoons of olive oil, the minced garlic and half of the mint. Season the lamb with salt and pepper. Roast for about 1 hour and 45 minutes, or until an instant-read thermometer inserted in the thickest part of the meat registers 130° for medium rare: Add water to the roasting pan occasionally if necessary to prevent the pan juices from burning. Transfer the lamb to a cutting board and cover loosely with aluminum foil. Leave the oven on.
Set the roasting pan over 2 burners, add the remaining 1 cup of water and bring to a boil over high heat, scraping up any browned bits from the bottom of the pan. Stir in the olives and the remaining half of the mint and pour the pan sauce into a bowl.
Rewarm the beans over moderate heat; add some of the reserved bean cooking liquid if they seem dry. Season with salt and pepper. Heat the Oven-Dried Tomatoes in the oven until warmed through. Spoon the beans onto a large platter and arrange the dried tomatoes around them. Thickly slice the lamb and arrange it over the beans. Pour the pan sauce over the lamb slices and serve.