Start by heating the olive oil and butter in a large pot or Dutch oven over medium-high heat. Thow in the stew meat and quicly brown it on all sides, about 5 minutes.
Remove the meat to a clean plate and set aside.
Throw the onion into the pot then reduce the heat to low.
Stir the onion around to cook until softened, about 3 minutes.
Then throw in the garlic and stir it around to cook for a minute.
Pour in the beer, beef broth, worcestershire sauce, tomato paste, paprika, sugar, salt and pepper.
Finally, return the meat to the pot, cover it and simmer the stew over very low heat for 1/12 to 2 hours or until the meat is very tender. If the liquid level gets too low, add 1-2 cups hot water as needed.
Add the potatoes, carrots and celery to the pot. Stir them in and continue simmering for 30 minutes more or until the vegetables are tender.
To thicken stew, remove 1 cup of the cooking liquid and whisk in the flour.
Pour the flour mixture into the pot and simmer for an additional 10 minutes, or until the stew is very thick. Add parsley to the end if desired.