Start by patting your beef dry and seasoning it generously with salt and pepper. Get your oven preheated to 325°F (160°C).
Heat 1 tablespoon of oil in a large Dutch oven over medium heat. Brown half of the beef chunks until they're nicely colored on all sides, then remove them to a bowl. Repeat with another tablespoon of oil and the rest of the beef.
Add the last tablespoon of oil to the Dutch oven. Sauté the diced onion and chopped celery for about 4 minutes until they soften.
Stir in the fresh rosemary (or thyme), tomato paste, and minced garlic. Cook for just 1 minute until you smell their wonderful fragrance.
Pour in the red wine and let it simmer for about 2 minutes until it reduces by half. Then, add the beef broth and bring it to a gentle simmer.
Return all the browned beef and any accumulated juices back into the pot. Cover tightly, transfer to the preheated oven, and cook for 1 hour.
Take the pot out of the oven. Stir in the chopped zucchini, cubed turnip, and optional chopped carrot. Return it to the oven and cook for another 30 to 45 minutes, or until the vegetables are tender and the beef is melt-in-your-mouth soft.
To thicken your stew, gently push the meat and vegetables to one side. Whisk the glucomannan (or xanthan gum) directly into the hot liquid. It will thicken as it stands. Serve warm and enjoy!