Trim the fat from the meat and cut into 1 1/2 inch pieces (You could also have the butcher cut it for you.)
In a gallon sized plastic bag, combine flour, thyme, and pepper. Add your meat to the bag, zip it closed and shake it to coat.
In a skillet, heat 4 Tablespoons of the oil over high heat. Add your meat and cook sear edges for about 4-5 minutes or until the outside edges of the meat are brown. Transfer it to your Slow Cooker.
Add in the onion, garlic, beef broth, tomato paste, diced tomatoes, diced potatoes, mushrooms, carrots, celery, salt and pepper.
Cover and cook on low-heat setting for 6 to 8 hours or on high-heat setting for 4 to 5 hours.
Sprinkle fresh parsley on top when ready to serve.