Heat a large pot over medium heat and add the beef stew meat. Cook until the pieces brown on all sides, about 5 minutes.
Add the onion, carrots, celery, and garlic to the pot. Stir and cook for 3 minutes until the vegetables begin to soften.
Pour in the beef broth, then add the pearl barley, diced tomatoes, thyme, and bay leaves. Stir to combine.
Bring the mixture to a boil, then reduce the heat to low. Cover and simmer for 45 minutes, stirring once or twice, until the beef is tender and the barley is cooked through.
Remove the bay leaves. Stir in the frozen peas and cook for 2 more minutes. Season with salt and black pepper to taste before serving.