2½ pounds topside beef with fat cap, cut into 8 to 10 generous ¼-inch slices
½ cup all-purpose flour, for dusting
2 tablespoons unsalted butter, plus more as needed
6 medium (2 pounds) waxy potatoes (such as Yukon Golds), peeled and cut into ½-inch rounds
2 medium white onions, thinly sliced
Two 12-ounce bottles pilsner beer (such as Tannenzäpfle or Stella)
2 bay leaves
4 cups low-sodium beef stock
Kosher salt and freshly ground black pepper, to taste
½ cup chopped fresh parsley, to serve
Assorted pickled vegetables, to serve
Directions
Preheat the oven to 300° and line a baking sheet with parchment paper.
Working in batches, place 3 beef slices in between 2 large pieces of parchment paper and pound with a mallet or heavy saucepan until ⅛ inch thick. Repeat until all of the slices are pounded. Set aside.
Pour the flour onto a large plate. Turn each slice of beef in the flour, coating both sides, and place in a single layer on the prepared baking sheet.
In a large wide Dutch oven or heavy-bottomed saucepan, heat the butter over medium-high heat. Working in batches, add a single layer of beef slices and brown both sides, flipping once, 4 minutes per side. Transfer the beef to a large plate and repeat with the remaining beef rounds, adding more butter as needed. Set aside.
Add the potatoes to the Dutch oven and sauté until golden brown, 10 minutes. Return the browned beef to the pot, along with the onions, and pour the beer over top. Add the bay leaves and enough beef stock to barely cover the meat and potatoes. Season with a generous pinch of salt and freshly ground black pepper. Cover and bring to a simmer, then transfer to the oven and braise until the meat is tender, 1½ to 2 hours.
Using a slotted spoon, divide the beef into bowls. Ladle the potato-onion broth into each bowl and sprinkle with the chopped parsley. Serve with the pickled vegetables.