Season the beef cubes generously with salt and pepper. Heat olive oil in a large Dutch oven or pot over medium-high heat. Brown the beef in batches, ensuring not to overcrowd the pan. Set aside.
Add the onion, carrots, parsnips, and celery to the pot and cook until softened, about 5-7 minutes. Add the garlic and cook for another minute.
Stir in the tomato paste and cook for 1 minute.
Pour in the red wine and deglaze the pot, scraping up any browned bits from the bottom.
Add the beef broth, Worcestershire sauce, thyme, rosemary, and bay leaves. Bring to a boil, then reduce heat and simmer for at least 2-3 hours, or until the beef is fork-tender.
Add the sweet potato and butternut squash to the stew and cook until tender, about 20-30 minutes.
Stir in the apple cider vinegar. If desired, thicken the stew with a cornstarch slurry (cornstarch mixed with cold water). Bring to a simmer and cook until thickened.
Season with salt and pepper to taste. Garnish with fresh parsley before serving.
