Add the flour and 1 teaspoon salt to a bowl (you could use a zip-top bag too!) and mix together. Add in the beef and toss until the beef is fully coated.
Heat the oil in a pan over medium/high heat and brown the beef on all sides. (Don't worry about cooking it through).
Once browned, remove the beef from the pan and add it to the slow cooker.
Lower the heat on the pan to medium. Pour in the Guinness beer and let it bubble for 30 seconds while you scrape up the bits from the bottom of the pan.
Carefully pour the heated Guinness from the pan to the slow cooker.*
Add the rest of the ingredients to the slow cooker and cook on low for 8 -10 hours or on high for 4-6 hours.
(Option) If you would like to thicken your beef stew for an even heartier feel:Mix together 2 tablespoons of flour or cornstarch with 3 tablespoons of water then stir the mixture into the stew. Cook for 30 minutes longer.
Garnish with parsley if you're feelin' fancy!
Notes
*If you don't want to use the beer, you could substitute red wine or even beef broth to deglaze the pan.