Arrange a rack in the lower third of the oven and heat the oven to 350°F.

Cook 4 ounces diced pancetta in a Dutch oven or heavy-bottomed pot oven-safe pot over medium heat, stirring occasionally, until lightly browned, 6 to 8 minutes.

Meanwhile, pat 1 (3- to 4-pound) boneless beef chuck roast dry with paper towels. Season all over with 2 teaspoons of the kosher salt and ½ teaspoon black pepper.

When the pancetta is ready, use a slotted spoon to transfer it to a large plate. Add the roast to the pot and sear until well-browned on 2 sides, 3 to 4 minutes per side. Transfer to the plate with the pancetta.

Add 1 diced large yellow onion, 2 peeled and diced large carrots, 2 diced medium celery stalks, 4 minced garlic cloves, and the remaining 1 teaspoon kosher salt. Cook, stirring occasionally, until the onions are softened, 5 to 8 minutes.

Stir in 2 cups dry red wine and bring to a boil. Boil for 1 to 2 minutes.

Stir in the reserved pancetta, 1 (14.5-ounce) can low-sodium beef broth, 1 (14-ounce) can crushed tomatoes, 2 dried bay leaves, 2 fresh thyme sprigs, and 1 fresh rosemary sprig. Bring to a simmer. Return the roast and any accumulated juices to the pot.

Cover and transfer to the oven. Cook until the meat is very tender and gently falling apart when pricked with a fork, 3 to 3 ½ hours.

Skim off some of the fat from the surface if desired. Remove and discard the bay leaves, thyme sprigs, and rosemary sprig.

Shred the roast into bite-size pieces right in the pot with tongs. Stir in 2 teaspoons balsamic vinegar if desired. Taste and season with more kosher salt as needed. Garnish with chopped fresh parsley leaves if desired.