Place each beef slice between sheets of plastic wrap and pound gently with a meat mallet until you reach 1/8-inch thickness. The meat should be thin enough to roll easily but not so thin it tears.
Combine the breadcrumbs, Parmesan, parsley, garlic, olive oil, salt, and pepper in a bowl, mixing until the olive oil is evenly distributed and the mixture holds together when pinched.
Lay each beef slice flat and spread 2 tablespoons of filling evenly across the surface, leaving a small border. Roll each piece tightly from one end, then secure with kitchen twine at both ends and once in the middle.
Preheat your oven to 325°F. Heat the olive oil in a heavy Dutch oven over medium-high heat until it shimmers and moves freely across the bottom of the pot.
Add the braciole and turn them every 2 minutes to brown evenly on all sides — you want a deep golden color that will add richness to the final sauce. Remove to a plate.
⏱ 8 min
Lower the heat to medium and add the diced onion to the same pot. Cook, stirring occasionally, until the onion is soft and translucent but not browned.
⏱ 5 min
Pour in the crushed tomatoes, wine, oregano, and salt, scraping up any browned bits from the bottom of the pot. Bring the mixture to a gentle simmer.
Nestle the braciole back into the sauce, cover the pot with a tight-fitting lid, and slide into the oven. The low, slow heat will make the beef incredibly tender.
⏱ 2 hrs
Carefully snip and remove all the twine before slicing and serving. The braciole should cut cleanly with a fork and the sauce should be rich and slightly thickened.