Season the roast on all sides with sea salt and black pepper.
Sea salt and freshly ground black pepper to taste
Melt some cooking fat over medium-high heat in a large skillet, and sear the roast for 2-3 minutes on each side.
2 tbsp. cooking fat
Place the meat in the slow cooker and top with the onion, minced garlic, balsamic vinegar, beef stock, bay leaves, rosemary sprigs, and red wine (if using).
1 onion, 2 sprigs of fresh rosemary, 2 bay leaves, 2 cloves garlic, 1 cup red wine, ⅓ cup balsamic vinegar, 1 ½ cup beef stock, 3 lb. beef chuck roast
Cover the slow cooker, turn it on low, and cook for 6 hours.
Add the carrots and sweet potatoes, set the slow cooker to high, and cook for about another 3 hours, or until the vegetables are nice and soft and the meat is fork tender.
4 carrots, 2 to 3 sweet potatoes
Remove and discard the 2 bay leaves and rosemary sprigs.
Pour the liquid from the slow cooker into a saucepan and bring to a slow boil over medium-high heat. Keep it boiling and let it reduce until you get the desired consistency for your sauce.
Pour the sauce back into the slow cooker and serve with the meat and vegetables.