Preheat oven to 325 F.
Heat 1 tablespoon oil in a Dutch oven set over medium heat. Add sausage and cook until well browned, breaking up into pieces with a wooden spoon or spatula. Remove to a plate and reserved, chilled, until ready to use.
In the same Dutch oven, heat another tablespoon of oil over medium heat. Season chuck roast all over with 2 teaspoons salt. Brown meat on all sides, at least 3-4 minutes per side. Remove to a plate and reserve. Turn heat to low and pour off fat.
Heat remaining olive oil in the pan. Add onions and garlic and sweat slowly until translucent. Season with red papper flakes and remaining salt. Pour in wine, increase heat to medium, and simmer rapidly until reduced by half, scraping up any brown fond that forms on the bottom.
Return the browned chuck roast to the Dutch oven. Cover with lid and cook in the oven for 1 hour. After an hour, carefully flip the roast. Continue cooking, covered, another hour or 90 minutes until the meat is fall-apart tender. Remove the roast to a large bowl, let cool slightly, then shred into small pieces.
Skim any fat from the liquid, then return the Dutch oven to the stovetop on medium heat. Return the shredded beef and sausage to the pot, along with the cinnamon stick, oregano sprigs, tomatoes and soy sauce. Bring to a rapid simmer, then reduce heat to low and simmer 45 minutes. Taste and season with additional salt if needed.
Serve ragu over warm polenta, garnished with Parmesan and fresh oregano.