01 - Pat the beef cubes dry with paper towels and season generously with salt and pepper.
02 - In a large Dutch oven or heavy-bottomed pot, heat 2 tablespoons of oil over medium-high heat. Brown the beef in batches on all sides, transferring to a plate as you go.
03 - Add the remaining oil to the pot and sauté onions until softened, about 5 minutes. Add garlic and cook for 1 minute until fragrant.
04 - Stir in the flour and cook for 1 minute, stirring constantly to form a roux and eliminate raw flour taste.
05 - Add tomato paste and stir for another minute to deepen the flavor base.
06 - Pour in the alcohol-free stout, scraping the bottom of the pot to release any browned bits. Add beef stock and Worcestershire sauce.
07 - Return the beef to the pot. Add carrots, parsnips, celery, potatoes, bay leaves, and thyme. Bring to a gentle simmer.
08 - Reduce heat to low, cover, and simmer gently for 2 hours, stirring occasionally, until the beef and vegetables are fork-tender.
09 - Remove the lid for the last 20 minutes of cooking to allow the stew to reduce and thicken to desired consistency.
10 - Remove bay leaves and thyme stems. Adjust seasoning with salt and pepper. Serve hot, garnished with fresh parsley if desired.