A while back, my husband and I were watching Man v. Food. In the episode we were watching, Adam went to an Italian Beef place in Chicago. Shortly after the episode was over, my husband suggested we try making them at home some day. So, we did. They were delicious. I can't say if they're authentic (though I would guess they're not), but they tasted great.
Recipe from CDKitchen.com
Prep Time - 5 minutes
Cook Time - 20 minutes
1 1/2 cups beef broth
1 cup water
3 TBSP tomato paste
1 bay leaf
1/2 tsp red pepper flakes
1 clove garlic, minced
1/2 lb thinly sliced roast beef
1 green pepper, thinly sliced
1 small onion, sliced
2 Italian rolls, sliced in half
Mix together the beef broth, water, tomato paste, bay leaf, pepper flakes, and garlic in a medium saucepan over medium heat. Let cook for about 5 minutes.
Add the peppers, onions, and beef. Cook for about 10-15 minutes.
Build the sandwiches by adding the meat, peppers, and onions to the bun. Dip the buns into the jus and serve.