Heat oil on medium in a large pot, add sausage slices and cook, stirring til fully browned, about 5 minutes
Stir in onions and continue to cook until onions are soft and begin to brown, 3-5 minutes
Stir in cabbage and garlic, season with salt and pepper and cover and cook another 5 minutes until cabbage softens a bit
Add beer and bring to a boil, then reduce to simmer for 5 minutes.
Add chicken stock and potatoes. Bring to a boil again then reduce to low and simmer for 40 minutes.
Stir in cider vinegar and then remove from heat.
Serve topped with fresh chopped parsley