Season cubed beef chuck with salt and pepper. In a large pot over medium-high heat, add olive oil and sear the beef until browned on all sides. Remove from pot.
In the same pot, sauté diced onion, celery, and carrots for about 5 minutes until softened. Add minced garlic and cook for an additional minute.
Deglaze the pot with red apple vinegar, scraping up any browned bits from the bottom.
Add low-sodium beef broth, Worcestershire sauce, fresh thyme, and the seared beef back into the pot. Bring to a gentle simmer for about 45 minutes.
Stir in pearled barley and continue to simmer for another 45–60 minutes until barley is tender.
Adjust seasoning to taste with salt and pepper before removing from heat. Stir in minced parsley just before serving.
