Hanger Steak Sandwich

1. In a small sauté pan, sauté mushrooms on medium high in 1 tablespoon of butter until cooked throughout and slightly golden.
2. Now to make caramelized onions: In separate sauté pan, heat another 1 tablespoon of butter and add in sliced onions. Sauté on medium high until translucent and soft. Add in brown sugar and allow to melt in. Then pour in beer 1/4 cup at a time. Allow beer to completely dissipate before adding more beer and then season with salt and pepper.
3. Season tenderloin with oil and salt and pepper and grill on a BBQ for 7-10 minutes, turning once or twice. You want the meat to be just over rare when done.
4. When the meat is done, allow to rest for five minutes and then begin slicing into the thinnest slices possible. Use a very sharp knife for this (DO NOT use a serrated blade).
5. In a small sauce pan melt the remaining 4 tablespoons (1/4 cup) of butter with the garlic and allow to cook for 5 minutes. Brush this on the loaf (sliced in half and then horizontally to make a sandwich).
6. Heat broiler in oven to high, pile meat onto the buttered loaves, top with cheese and broil until golden and bubbly. Done!