Melt the butter in a large Dutch oven over medium-high heat. Add the onion and cabbage, season with a large pinch of salt and cook until the vegetables begin to melt and break down, 10 to 12 minutes. Stir in the cider, beer, red pepper flakes, coriander, pureed sauerkraut and ham hock. Bring to a simmer and cook for 30 minutes to let the flavors meld.
Nestle the pork and sausage in the Dutch oven and continue to simmer for 45 minutes, until all of the meat is cooked through and tender. After 45 minutes, remove the ham hock, pork and sausage to a cutting board. Slice all of the meat and add it back into the pot. Mix in the parsley and mustard and additional salt and pepper, if needed.