Heat a large Dutch oven
over medium-high heat. Add the bacon and cook until crisp, about 5 minutes. Add the onions along with a pinch of salt and cook until the onions
are translucent, 3 to 5 minutes. Add the beer
, vinegar and another large pinch of salt. Cover and cook until the cabbage is wilted but is still slightly crisp
. Stir in the mustard and taste for seasoning. You might want to add some additional salt, mustard
and/or vinegar at this time.
Remove the cabbage from the heat and stir in the chives and parsley.