In a large pot over medium-high heat, add the beef, onion, garlic, and celery. Sauté for about 5 minutes, stirring occasionally.
Add the beef broth, Worcestershire sauce, thyme, bay leaf, and black pepper. Bring to a boil and reduce heat to a simmer. Simmer for 45 minutes, stirring occasionally.
In a small bowl, whisk together the flour and butter to make a paste. Gradually stir the paste into the soup and simmer for an additional 10 minutes.
Add the carrots, peas, and parsley. Simmer for 10 minutes, stirring occasionally.
Remove from heat and serve warm.
Interesting Facts
Brown Jug Soup is a tradition in some parts of the U.S., and has been served for generations.
The name "Brown Jug Soup" comes from the old tradition of using a brown jug to store the soup.
This soup is a great way to use up leftovers, so you can add whatever vegetables or protein you have on hand.