"I don't remember exactly why, but for the longest time I've wanted to try stuffing and braising a beef flank steak, and this very brociale-like roulade was the result. And while the outside was an unsightly mess of frayed meat fiber, the overall dish was a delicious success."
Butterfly the steak by cutting horizontally into the long side of the steak, through the middle, to within one-half inch of the other side. Open the steak and spread the sides out like an open book. Cover the steak with plastic wrap and pound it with a meat mallet to give it an even surface. Discard the plastic wrap.
Season steak with salt and pepper. Scatter 3 tablespoons bread crumbs, parsley, currants, and pine nuts over the steak; season with cayenne pepper and red pepper flakes. Spread slices on the steak and sprinkle Parmigiano-Reggiano cheese and remaining bread crumbs over the top.
Roll up meat firmly, starting at a cut-end, and set seam-side down. Use kitchen twine to tie steak at 1-inch intervals. Season with salt.
Heat olive oil in a large pot over medium-high heat. Cook steak until brown on all sides, 3 to 5 minutes per side.
Pour tomato sauce, chicken broth, white wine, and bay leaf into the pot; add enough water to just cover the steak. Bring liquid to a simmer, reduce heat to low, cover pot with a lid, and braise until meat is fork-tender, 2 1/2 to 3 hours. Transfer meat to a plate to rest for 10 minutes before slicing across the grain.
Increase heat to medium-high and cook liquid until it is reduced and slightly thicker, about 10 minutes. Spoon sauce over sliced beef.