This recipe originates in Flanders where Savoy cabbage is much loved.
The stock is made into a quick pea soup and served as a first course.
It is similar to the French Pot au Feu although the former has peas and the latter garlic and leeks.
Cover the beef, pork, pork bone, bay leaves and peppercorns in water in a large pot and bring to a simmer.
Skim the foam away and cover; simmer 2 1/2-3 hrs until the meats are tender.
Add the salt during the last hour.
Prepare and reserve the vegetables.
Wash the potatoes; do not peel if new.
Wash, trim, core and cut the cabbage into 8 wedges.
Peel and quarter the turnips.
About 30 min before the meat is done add the potatoes and turnips.
Remove the meats and vegetables from the broth; arrange the vegetables around the meat on a large platter, cover with foil and keep warm.
Discard the pork bone.
Strain the broth through cheesecloth and reserve 2 cups for the pea soup, returning the rest to the pot to cook the cabbage in.
Simmer the cabbage 5-7 min until tender and remove; arrange on the meat platter.
Meanwhile cook the peas in a separate smaller pot; puree in a blender with the reserved broth in small lots until smooth.
Strain through a wire sieve discarding the pulp.
Re-heat and serve as a first course garnished with croutons and chives.
Then bring the hot platter to the table; slice meat and serve with mustard and horseradish.
To adapt to a crockpot I would suggest[but have not tested] about 10-12 hrs on low for the meats, perhaps 4 hrs for the potatoes and turnips and do the cabbage with the meats and vegetables say the last 30 min.
Do the peas separately on the stove at the last minute.