For the mushroom sauce:
1. add butter to a hot skillet and cook until melted. Add the onions and saute until tender. Next, add the rosemary and mushrooms, cooking until the mushrooms are browned and tender. Add in the flour and mix until the vegetables are well coated.
2. Pour in the Worcestershire sauce, red wine, beef broth, and heavy cream. Allow this mixture to simmer until the mixture reaches a spoon-thick consistency.
For the Sandwich:
1. Add oil to the griddle. Once hot, add your shaved beef, seasoning to taste. Cook the beef until its well brown on each side, flipping as needed.
2. Once the steak has browned, form a small pile with the beef and top with Swiss cheese. Place an open hoagie roll on top of the cheese & steak mixture and flip with a spatula so that the cheesy side is on the bottom of the hoagie roll. Allow the hoagie to toast on the griddle for 30 seconds – 1 minute, then remove from the heat.
To Finish:
1. Top the sandwich with the mushroom sauce. Repeat this process as desired and enjoy!
