Preparation

• Tie the parsley, thyme, and bay leaf in a 10-inch square of cheesecloth with kitchen string to make a bouquet garni. Tie the leeks into a bundle.
• Put all of the meat in a 10- to 12-quart stockpot. Cover with cool water by 1 inch and bring to a boil over medium-high heat.
• Meanwhile, bring a 6- to 8-quart pot of salted water to a boil, add the cabbage, and boil for 3 minutes. Drain and set aside. (Blanching the cabbage keeps its flavor from overpowering the broth.)
• Skim the surface of the liquid in the pot, and add the bouquet garni, leeks, cabbage, carrots, turnips, garlic, onion, 7/8 oz. salt (about 2 Tbs. Diamond Crystal or 1-1/2 Tbs. Morton), 1/2 tsp. pepper, and enough water to just cover the meat and vegetables. Return to a boil, skim again, turn the heat down to low, and partially cover. Cook at a very gentle simmer, skimming off any foam, until the vegetables are tender and the meat is very tender. The meat will take 2-1/2 to 3 hours, but start checking the cabbage after 30 minutes and the other vegetables after 1 hour; transfer each to a platter as it’s cooked.
• Meanwhile, boil the potatoes separately in lightly salted water until tender, about 20 minutes, and drain. Set aside.
• Transfer the meat to a large platter and cover with foil to keep warm. Discard the bouquet garni. Put the potatoes and the other cooked vegetables into the broth to reheat for a few minutes, then transfer them to the platter with the meat. Ladle enough broth over the meat and vegetables to keep them moist, cover with foil, and keep warm in a low oven. Strain the broth if you think it needs it (I generally don’t).
• Serve some of the hot broth as a first course along with the toasted baguette slices. (You won’t use all of the broth; save it for another use, such as a soup, braise, or sauce.)
• Serve the meat and vegetables as the main course along with small bowls of flaky salt, mustard, and cornichons.