Heat olive oil in a large pot or Dutch oven over medium-high heat. Brown beef stew meat in batches, then set aside.
Add onion, carrots, and celery to the pot and cook until softened, about 5-7 minutes.
Add garlic and cook for 1 minute more.
Return beef to the pot. Add beef broth, diced tomatoes, thyme, and bay leaf. Bring to a boil, then reduce heat and simmer for at least 1.5 hours, or until beef is very tender.
Add potatoes and continue to simmer for 20 minutes, or until potatoes are tender.
Stir in frozen peas and cook for 5 minutes more. Remove bay leaf before serving. Season with salt and pepper to taste.