Heat the olive oil in a large soup pot or Dutch oven over medium-high heat. Add the beef cubes in a single layer (do this in batches if needed) and sear on all sides until browned. This helps build deep flavor. Remove the browned beef and set aside.
In the same pot, add the chopped onion, carrots, and celery. Sauté for 5–7 minutes until the veggies begin to soften. Add garlic and cook for another minute until fragrant.
Stir in the tomato paste and cook for 2 minutes to deepen its flavor. Add the thyme, rosemary, and a pinch of salt and pepper.
Return the seared beef to the pot. Pour in the beef broth and water. Scrape the bottom of the pot to release any browned bits (flavor gold!). Add in the bay leaf and Worcestershire sauce. Bring everything to a boil.
Once boiling, reduce the heat to low. Cover partially and let it simmer for about 1 hour, or until the beef is tender.
Stir in the rinsed barley and simmer for another 35–40 minutes, uncovered, stirring occasionally to prevent sticking. Add peas during the last 5 minutes if using.
Remove the bay leaf. Taste and adjust seasoning with additional salt and pepper if needed. Serve hot with fresh parsley sprinkled on top and a side of crusty bread if desired.