01 - Pat the beef cubes completely dry with paper towels. Season generously with salt and pepper, coating all sides evenly.
02 - Heat 2 tablespoons olive oil in a large Dutch oven or heavy-bottomed pot over medium-high heat. Brown the beef in batches, being careful not to overcrowd the pan. Sear each batch until deeply browned on all sides, approximately 3-4 minutes per batch. Transfer browned beef to a plate and set aside.
03 - Add the remaining 1 tablespoon olive oil to the pot. Sauté onions and celery until softened and translucent, about 5 minutes. Add minced garlic and cook for 1 minute until fragrant, being careful not to burn it.
04 - Stir in tomato paste and cook for another minute until it darkens slightly and becomes fragrant. Pour in the red wine, using a wooden spoon to scrape up any browned bits from the bottom of the pot. Simmer for 2-3 minutes to reduce slightly and concentrate flavors.
05 - Return the browned beef and any accumulated juices to the pot. Add carrots, parsnips, potatoes, and rutabaga. Pour in the beef stock and add bay leaves, thyme, and rosemary. Stir to combine all ingredients.
06 - Bring the mixture to a gentle simmer, then reduce heat to low. Cover and cook for 2 to 2.5 hours, stirring occasionally, until beef is fork-tender and vegetables are cooked through. The stew should bubble gently throughout cooking.
07 - For a thicker consistency, mix cornstarch with cold water in a small bowl to create a smooth slurry. Stir the slurry into the stew and simmer uncovered for 5-10 minutes, stirring occasionally, until the desired thickness is reached.
08 - Remove and discard bay leaves and herb stems. Taste and adjust seasoning with additional salt and pepper if needed. Serve hot in warmed bowls, garnished with fresh thyme or rosemary if desired.