in a large dutch oven, cook the bacon on medium heat until crispy. remove the bacon using a slotted spoon & drain on paper towels. sear the sausage (or bratwurst) in bacon grease to brown. remove the sausages from the pan to drain with the bacon.
remove all but about 1/4 of bacon grease from the pan. add the sliced onion to the pot, & cover. cook for about 7 minutes, stirring once or twice. add in the chicken broth, apple cider vinegar, minced garlic,& a sprinkling of pepper. bring to a boil, then remove from the heat. pour the onion/broth mixture into a separate dish for a moment.
layer the sliced potatoes along the bottom of your dutch oven. pour the onion/broth mixture over top. add in 1/2 of the bacon & 1/4 cup of chopped fresh parsley. place the whole sausages on top.
cover, cook for 45 minutes. romove from the heat & pour in 1 cup of guinness beer ( or broth). replace the cover & return to the oven for another 45 minutes.
top with the remaining bacon & a few more sprink;es of fresh parsley once it's done. serve with crusty bread to sop up the au jus