For bollito misto, boil the stock about 1 liter of water with white wine, peppercorns, bay leaves, herbs, onions, garlic and some of the celery (save the rest for the chowder) together and salt lightly.
Remove the end bone from the rabbit legs and cook the legs in the stock for 20-25 minutes. Once tender, lift out and set aside and strain the stock.
Reheat and for the chowder, cook carrots, turnips, remaining celery, and pea pods in it, one at a time (depending on the cooking point) until soft. Then strain and set aside a total of 300 ml of stock.
Now boil up the vegetables with about 100 ml of Bollito stock and the butter and reduce until the stock is nice and creamy. Season to taste with salt and pepper.
Meanwhile, add the rabbit legs back into the stock and simmer gently for about 5 minutes. Then add in the beef tenderloins and after another 2-3 minutes add the foie gras. Simmer for another 4 minutes, depending on the desired degree of cooking.
For the sauce, bring the stock and white wine to a boil and reduce by about a third. Blend the cold butter into the sauce with the foie gras, strain and season with salt and pepper.
Now, in large warmed soup plates, first arrange the vegetables, place the meat on top and finally pour the sauce over Bollito misto.