Preheat the oven to 300ºF, and position a rack in the center or one notch down. You might need to remove the top rack to have enough room for the pot with its lid and handle.

Heat the oil over medium-high in a 4-quart braiser or Dutch oven (with a lid) until shimmering.

Add the bacon, layering the pieces across the surface of the pot. Cook, stirring often until browned. This will take 10 to 20 minutes, depending on how wide your pot is (the wider the pot, the more hot surface area for the bacon to rest on). Transfer the cooked bacon to a paper-toweled lined plate, and drain off all but about a tablespoon of the rendered bacon fat.

Add the sausage to the pot. Stir often, browning the outer sides and edges, about 5 minutes. The sausage pieces will not be cooked all the through at this point; that’s okay.

Return the bacon to the pot.

Stir in the cabbage, about half of the parsley, and the Guinness, mixing well with the meat. Let the beer come up to a simmer and spoon in the mustard. Give everything a good stir, and cook for 5 minutes, which cooks off the alcohol in the beer.

Layer the onions on top, and gently stir to coat them with the sauce in the pot. Smooth everything out into an even layer.

Pour the chicken broth over the mixture, adding just enough to bring the liquids even with the onions. (You might use a little more or less than 2 cups; you can use water if you need more liquids.)

Layer the potato chunks on top of the mixture; do not stir. They will not be covered with the broth. (Don’t forget to turn off the stove top heat.)

Place the lid on the pot, and then put the pot in the oven.

Cook for 2 1/2 hours. Remove the lid and cook for another hour (don’t disturb the potatoes).

Before serving, giving the stew a good stir to bring the sausage and bacon to the top. Add the remaining parsley and green onions as a garnish.