Brown the cubed stew beef. In a large saute pan, add the oil and heat. Using tongs, place beef into the pan and cook until the beef gets a nice golden brown color, turn the beef over and brown the other side. Add the garlic and cook for 1 minute. Add the beef to the slow cooker. Pour about 1/3 cup of broth into the sauce pan, scraping the sides to get all the droppings. Pour into the crockpot.
Add all ingredients to the slow cooker. Add the sugar, balsamic vinegar, bay leaves, ground thyme, salt, potatoes, carrots, parsnips, onions, beef broth, and beer to the crockpot. Cover.
Cook the beef stew. Cook on high for 6-8 hours or low for 8-10 hours. Season with additional salt if needed.
If you prefer a thicker beef stew, create a cornstarch slurry by mixing 1 tablespoon of water with 1 tablespoon of cornstarch in a bowl then pouring into the slow cooker about 30 minutes before the stew is done cooking.
Store in the fridge for up to 5 days or in the freezer for up to 3 months.
Stick with only using root vegetables to prevent mushy veggies.
Swap the Guinness with a gluten free beer and double check the ingredient labels of the balsamic vinegar and beef broth to create a gluten-free stew.