In a large pot, heat the olive oil over medium-high heat. Add the beef stew meat and brown on all sides, about 5-7 minutes. Remove the beef and set aside.
In the same pot, add the chopped onion and garlic. Sauté for 2-3 minutes until the onion is translucent.
Add the carrots, celery, and potato to the pot. Cook for another 5 minutes, stirring occasionally.
Return the browned beef to the pot. Add the diced tomatoes, beef broth, thyme, oregano, bay leaf, salt, and pepper. Bring to a boil.
Reduce heat to low, cover, and simmer for 1.5 to 2 hours, or until the beef is tender.
About 10 minutes before serving, stir in the frozen peas and green beans. Cook until the vegetables are heated through.
Remove the bay leaf before serving. Garnish with fresh parsley if desired.