This hearty stew throws in everything but the kitchen sink. You should have leftovers.
Preheat oven to 425 degrees. Arrange veal bones in a heavy-bottomed roasting pan. Place in oven and roast, turning occasionally, until light golden brown, about 1 hour.
Transfer veal bones to a 20-quart stockpot. Tie up each short rib with kitchen string. Add short ribs, brisket, and enough cold water to cover the meats (about 6 1/2 quarts). Bring to a boil over high heat. Reduce heat to medium, and skim off any fat and scum that form on the surface. Simmer for 30 minutes, skimming as necessary.
Trim dark-green tops from leeks, and reserve them. Cut leek bottoms in half lengthwise, and place in a bowl of cold water. Soak for 10 minutes to rid them of sand. Lift out, drain, and set aside. Add onions, 2 medium carrots, half the leeks, and 1 tablespoon salt to the stockpot. Wrap thyme, garlic, white and black peppercorns, cloves, parsley stems, and bay leaves in cheesecloth, tie with kitchen string, and add to stockpot along with 1 quart water. Return to a boil, reduce heat to medium low, and let simmer. After 1 hour and 15 minutes, turn on oven to 425 degrees. and preheat for 15 minutes.
Prepare chicken: rinse it inside and out, pat dry, tie the legs together with kitchen string, and tuck wing tips underneath body. Place in a roasting pan, and roast until golden brown, about 30 minutes. Transfer to the simmering stockpot, and add water to cover (about 3 quarts). Bring to a boil, reduce heat to medium, and simmer for 45 minutes (the stock should simmer a total of 2 hours and 45 minutes), skimming the surface as necessary. If the chicken cannot be completely immersed in the water, turn it after 20 minutes to ensure even cooking.
Remove stockpot from heat. Remove the meat and chicken from the stockpot; set meats aside. Strain the broth into a large bowl through a cheesecloth-lined sieve, and discard solids. Let meat and broth cool, and refrigerate them overnight.
Continue the preparation the next day. Heat oven to 375 degrees. Rub salt on cut sides of marrow bones. Rinse the reserved leek tops in cold water, and cut into 20 strips, 1/2 inch by 9 inches. Crisscross 2 strips of leek tops over each marrow bone, and bind with kitchen string. Place marrow bones in a small roasting pan, and add just enough cold water to cover (about 1 1/2 cups). Cover roasting pan with aluminum foil, and bake until marrow is opaque, about 1 hour. Remove from oven, keep covered, and set aside.
Meanwhile, remove broth from refrigerator, and skim off any fat that has solidified on the surface. Return the broth to the 20-quart stockpot, and bring to a boil. Add remaining leeks, and cook over medium-high heat for 25 minutes. Adjust seasoning with salt and pepper to taste. Add brisket, short ribs, chicken (cut in half), celery hearts, baby carrots, and potatoes, and cook until vegetables are tender, about 20 minutes more.
Meanwhile, bring a large pot of salted water to a boil. Add haricots verts, and cook until tender but still slightly crunchy, about 3 minutes. Remove with a slotted spoon, and set aside in a medium bowl; cover with aluminum foil. To the same water, add cabbage, and cook over medium-high heat for about 15 minutes. Add turnips and cook until both are tender, about 15 more minutes. Drain, cut each cabbage wedge in half, and set aside in a large bowl; cover with aluminum foil to keep warm.
Slice baguette diagonally into 1/2-inch slices, and toast on a baking sheet in the heated oven until golden brown, about 10 minutes.
When all the vegetables are tender and the meats and chicken are warmed through, remove meats and chicken from broth. Prepare the meats and potatoes for serving (and keep them, covered, in a warm oven while you complete the process): slice the brisket into 1/4-inch slices. Remove bones from chicken breast; cut each half into three pieces, and cut legs from thighs. Untie short ribs, remove gristle, and cut each piece in half. Cut potatoes into 1/4-inch slices. Adjust the seasoning of the broth with salt and pepper to taste. Divide meats, chicken, marrow bones, vegetables, and broth among eight serving bowls. Serve immediately with toasted bread, mustard, olives, cornichons, horseradish, and salt. Strain any remaining broth through a fine-mesh strainer, and freeze for future use.
Pot-au-feu requires more attention than preparation. All the cooking times are approximate, so if something seems to be done sooner than the recipe indicates, remove it and set it aside.