Slow Cooker Guinness Brew Beef Stew

2 lbs. new red potatoes, scrubbed and cut in half
4 carrots, chopped coarse
2 celery stalks, chopped coarse
2 bay leaves
3 lbs stew beef, cubed
1/2 cup flour, season with salt and pepper
3 Tbsp olive oil
1 medium onion, diced
4 garlic cloves, minced
1 can (15 oz size) beef broth
8 oz. fresh whole mushrooms, cut in half
2 (8 oz. each) can tomato sauce
1 envelope dry onion soup mix
1 tsp dried thyme
1/2 tsp dried oregano
1/2 tsp dried marjoram
1 tsp dried basil
1 tsp salt
12 oz. Guinness Stout Beer (or other very dark beer)

Put the potatoes, carrots, celery, and bay leaves in the crockpot.
Put the stew beef in a paper bag and add the flour that has been seasoned with salt and pepper; shake the bag to coat the beef.
In a large skillet, add the olive oil, heat over medium-high heat, and brown the coated beef stew meat in the skillet, removing as it cooks, and set aside.  (Do this in batches so you don't overcrowd the skillet.)
When beef is all browned, add onion and garlic to the same skillet and cook for 1 minute, then pour in the beef broth and let cook for 1 more minute, scraping the browned bits off the bottom of the skillet.
Now put the browned beef in the crockpot, along with the onion/garlic/broth mixture from the skillet.  Add the mushrooms, tomato sauce, onion soup mix, and all seasonings, stir gently.
Pour in the Guiness, then cover the crockpot, set heat to LOW, and cook for 7 to 8 hours.
Serve in big bowls with crusty bread along side.
Serves 4 to 6.