Heat the olive oil in a large pot or Dutch oven over medium-high heat. Add the beef cubes and brown them on all sides, approximately 5-7 minutes. Remove the beef and set aside.
In the same pot, add the diced onion, and sauté for 3-4 minutes until translucent. Then, add the minced garlic and cook for another minute until fragrant.
Add the sliced carrots and diced celery to the pot, stirring occasionally for about 5 minutes until the vegetables start to soften.
Return the browned beef to the pot. Then add the diced tomatoes, pearl barley, beef broth, dried thyme, dried rosemary, bay leaf, salt, and pepper.
Bring the soup to a boil, then reduce the heat to low and cover. Let it simmer for about 1 hour, stirring occasionally.
After one hour, add the green peas and allow the soup to simmer for an additional 20-30 minutes, or until the barley is tender and the beef is cooked through.
Remove the bay leaf before serving. Taste and adjust seasoning if necessary. Serve hot, garnished with fresh parsley if desired.