Place the beef strips in your slow cooker. Add in the grated garlic, Worcestershire sauce, salt, & pepper.
Slice the onion. Cut it into strips vertically. This will allow the onion to hold some of its texture while it cooks instead of turning into mush.
Cut the green bell pepper into strips.
Add those to the slow cooker along the beef broth.
Cover and cook on low for 5-6 hours.
To serve, place a couple slices of Swiss or provolone cheese on the bottom half of your roll. Pop it in the toaster oven for half a minute or so to melt the cheese. This is totally optional, but I just adore gooey cheese. Scoop some of your beef, peppers, & onions on top and cover with the other half of the roll.