Place the flour in a resealable plastic bag. Add the beef to the bag, several pieces at a time, and shake to coat completely.
Heat a large saute pan over medium-high heat and add the oil. In batches if necessary, add the beef and cook, turning, for 8 to 10 minutes, until browned on all sides. Using tongs, transfer to paper towels to drain.
Place the beef, potatoes, carrots, onions, and thyme in the slow cooker and pour the beer over the top. (If you perfer the vegetables with more texture, let the stew cook for 1 hour before adding the vegetables.)
Cover and cook on low for 8 hours, or until the meat is very tender. Season with salt. Remove and discard the thyme.