Combine the flour, salt and pepper in a bowl. Toss the beef cubes until they are completely coated. Set aside.
Fry the bacon in a Dutch oven or heavy pot until tender-crisp. Remove the bacon to a plate.
Using the bacon drippings, fry the flour coated beef in batches until browned on all sides. Transfer the beef to a plate.
Add the onions to the pan and sauté until softened. Add in the garlic and sauté until fragrant, around two minutes.
Pour a small amount of the Guiness into the pan, deglazing the bottom of the pot by scraping up the browned bits off of the bottom.
Add in the remaining beer, Worcestershire sauce, beef broth, tomato paste and sugar,
Place the beef. bacon, bay leaves, thyme and vegetables into the pot. Stir until combined.
Bring the stew to a low boil.
Reduce the heat to low, cover and simmer for 2 hours or until the beef and vegetables are tender. Stir every 30 minutes to ensure nothing is sticking to the bottom of the pot.
Remove the bay leaves and thyme.
Serve over mashed potatoes. The stew should be thick and perfect for over potatoes.
Notes
* if you are not making mashed potatoes, add in 3 large washed and chopped Russet potatoes to the stew