Into a large soup pot over medium-high heat, add the vegetable oil. When the oil is hot, add the onions. Cook, stirring frequently for 3 minutes, or until softened.
Add the garlic and continue cooking for an additional 30 seconds. Sprinkle with flour and stir to coat.
Add the potatoes and carrots. Stir in beef-style broth, beer, Worcestershire sauce, tomato paste, salt, thyme, and black pepper.
Bring just to a boil then reduce heat to low. Cover and simmer 20 minutes, or until vegetables are fork-tender. Remove cover and cook for an additional 15 minutes, until broth is thickened slightly. Adjust seasoning to taste.
Spoon into soup bowls, sprinkle with parsley, and serve hot.