Preheat an aluminum slow cooker insert or cast iron skillet on high heat.

Season the beef with half the salt and all the pepper.

Add to the skillet and brown on each side for 4-6 minutes or until deeply browned on each side.

Remove the beef from the pan and add in the onions.

Cook the onions for 3 minutes, stir then cook another 3 minutes.

Into the slow cooker add the onions, carrots, potatoes, broth, second half of the salt, tomato paste, bay leaf, thyme, garlic and Worcestershire sauce.

Cut the beef into 2-3 inch chunks and add it to the slow cooker.

Stir all the ingredients until well mixed and cook on low for 7 hours.

In a small bowl mix the butter and flour and add it to the slow cooker and stir.

Cook an additional hour or until thickened.