Combine all of the ingredients except the flour in the bowl of the slow cooker. Stir gently. Cover and cook on low for 10-12 hours.
Remove a ladle of broth from the stew to a container with a cover and add flour (2 tbsp to start). Cover and shake vigorously until combined. Stir into the stew. Repeat until you reach desired thickness.
Serve immediately. Leftovers can be stored in an airtight container in the fridge for up to five days.
Recipe by Sarah's Cucina Bella at http://sarahscucinabella.com/2012/01/06/slow-cooker-beef-and-veggie-stew/