In a dutch oven cook bacon over a medium high heat until desired crispness, remove and set aside.
Season beef with salt and pepper.
Add olive oil to dutch oven and brown the beef, remove and set aside.
Add butter and onions, cook until onions are soft and translucent, 2-3 minutes.
Add in flour and whisk to make a roux, cook for 1 minute.
Pour in Guinness and whisk until there are no more lumps.
Add tomato paste, beef stock, carrots or parsnips, potatoes, Worcestershire sauce, celery, bay leaves and thyme, stir to combine.
Return beef and bacon to the pot.
Bring to a boil, then reduce to low, cover and simmer for up to 2 hours, or until sauce has thickened to a loose gravy and vegetables are fork tender.
Taste and add salt and pepper as needed, remove bay leaves and enjoy.
Notes
You may use chicken broth in place of beef. The chicken broth will mask the taste of the Guinness more.Refrigerate the leftovers in an airtight container for up to 5 days.