Irish Bubble and Squeak

1 tablespoon duck fat
4 (1/4-inch thick) slices of smoked pork jowl, cut into chunks
1 medium onion, chopped
8-10 ounces brussels sprouts, ends trimmed and then shredded
14 ounces boiled potatoes, at room temperature (~3 small-medium)
salt, to taste
pepper, to taste

Put the duck fat in a large, nonstick skillet over medium heat.
Add the jowl and cook until golden all around, about 7 minutes.
Just eyeballing it, if you have more than 2 tablespoons of fat in the bottom of your skillet,
pour the excess into a small bowl or jar and reserve (in case you need to add more later).

Add the onion to the pan and cook until it has started to soften, stirring often
(a wooden spoon or rubber spatula works well here), about 5 minutes.
Add the shredded brussels sprouts to the pan and continue to cook, stirring often, until it is soft and tender, about 10 minutes.
pork jowl, onion, and shredded brussels sprouts.
Add the potatoes to the pan and sprinkle with a smattering of salt and a few good grinds of black pepper.
Use a potato masher to mash the potato into everything else, then switch back to your wooden spoon or rubber spatula.
Stir everything around it until everything is combined and then push and press it into the pan to form a sort of thick pancake.
Lift the edge of the mixture and if the pan looks very dry, drizzle in just a bit of the reserved fat while you lift the mixture up,
letting it get to the bottom of the pan. Continue to cook until you the mixture has turned golden and a bit crisp on the bottom and edges.

Slide (or flip) mixture onto a serving plate. Cut into wedges and serve alongside leftover roast meat or with an over-easy egg on top.