Put the first four dry ingredients in a large ziploc bag. Add the stew beef in the bag and shake vigorously to ensure all pieces are coated.
Add 2 Tbsp. of olive oil to a large saucepan and turn on heat to high. Once your pan is hot, add the stew meat. Keep turning the pieces until they are all browned. Transfer the meat to the slow cooker.
Prepare the vegetables by washing thoroughly and dicing the celery, onion and garlic. Saute these in a small frying pan with a small amount of olive oil. Once this step is complete, add to the slow cooker.
Scrub the potatoes and carrots. Dice into bite-size portions and add to slow cooker.
Add beef broth, Worcestershire sauce and Italian seasoning to the mixture, stirring well.
Cover and cook on low for 8 hours.