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.
nutrition information (per serving):
16, Fat Calories
140, Saturated Fat
40, Monounsaturated Fat
43, Polyunsaturated Fat
Photo: Scott Phillips