Heat the olive oil in large skillet or dutch oven, medium-high heat.
Salt and pepper beef, dust with flour and fry until browned on all sides, about 5 to 7 minutes. (work in batches to avoid overcrowding pan)
Remove from pan and set aside.
Add more oil to skillet if necessary. Next add potatoes, celery, carrots, and onion to skillet Cook until potatoes slightly browned (about 10 mins)
Remove from skillet, set aside.
Add butter to skillet.
Add garlic and sauté about 1 minute, until fragrant.
Deglaze pan with red wine. Add Guinness beer, beef stock, tomato paste, sugar, Worcestershire sauce, thyme and bay leaves.
Stir to combine and bring the mixture to a simmer. Next, add beef and vegetables back into the skillet or dutch oven.
Cover and transfer to oven to bake at 350 degrees for 1-2 hours until vegetables and beef are tender.
If using slow cooker, cook 3-4 hours on low.
If stew needs to be thickened add slurry (1 tablespoon flour whisked together with 1 tablespoon cold water). Return pot to stovetop and over medium heat slowly stir slurry into the stew stirring constantly. Cook 5-10 minutes until thickened
Season with salt and pepper to taste.