In a large skillet, heat the olive oil over medium-high heat. Add the beef cubes and brown on all sides, about 5-7 minutes. Remove the beef and set aside.
In the same skillet, add the onion and garlic. Sauté until the onion is translucent, about 3-4 minutes.
In a slow cooker, combine the browned beef, sautéed onion and garlic, carrots, celery, red bell pepper, diced tomatoes, beef broth, Worcestershire sauce, thyme, oregano, salt, and pepper.
Stir to combine all ingredients. Cover and cook on low for 6-8 hours or on high for 3-4 hours, until the beef is tender.
About 30 minutes before serving, stir in the frozen peas. Cover and continue cooking until heated through.
Serve hot, garnished with fresh parsley.