Spray crock pot with non-stick cooking spray.
Cut meat into strips, place in slow cooker.
Add green pepper, onion, broth, and dressing mix.
Cover and cook on low 7-8 hours, or high 3-4 hours.
Spoon meat mixture onto bread, top with a slice(s) of cheese.
Another option is to toast bread in a 375 degree oven for 5-10 minutes, add meat, cover with cheese, then bake an additional 5 minutes to melt the cheese.