Combine beef, celery, carrots, red onion, potatoes, salt, pepper, garlic, parsley, oregano, Worcestershire sauce, beef broth, and tomato paste in the crock pot. Cook on LOW for 10 hours or on HIGH for 6-7 hours. About 30 minutes before serving, mix the flour and the water together in a small dish and pour into the crockpot. Mix until well combines. Next add in your frozen peas and corn. Continue cooking covered for 30 minutes.