Philly Beef Sandwiches with Parmesan Horseradish Mayo

"These sandwiches are delicious.  The combination of roast beef and horseradish is a classic and these sandwiches bring the combo together perfectly!"

1 medium sweet onion, sliced
1 green pepper, sliced
2 Tablespoons canola oil
Leftover shredded roast beef or I have used 1 pound of shaved Angus roast beef from the deli
4 Slices of mozzarella, Swiss or provolone cheese
4 Hoagie rolls
packet of Au jus, we love Knorr brand
Parmesan Horseradish Mayo (Recipe follows)

In a saute pan, heat canola oil and add sliced onion and green pepper.  Saute for about 15 minutes or until vegetables are tender.  While vegetables are cooking, prepare Au jus packet, following package directions.  Add roast beef to the Au jus and simmer to heat thoroughly.  Prepare Parmesan Horseradish Mayo.


Parmesan Horseradish Mayo
1/3 cup mayonnaise
2 Tablespoons prepared Horseradish
1 Tablespoon grated Parmesan cheese
Salt, pepper and garlic powder, to taste

Combine all ingredients.


To Assemble Sandwiches:

Split hoagie rolls and place on baking sheet.  Layer sliced cheese on bottom of hoagie rolls.  Using tongs, remove roast beef from the Au jus and place on top of the cheese.  (The tongs will allow the Au jus to drain off of the roast beef so the bread doesn't get too soggy.)  Top with onions and green peppers.  Slather hoagie roll tops with Parmesan Horseradish Mayo and place on top of the onions and green peppers.  Place sandwiches under the broiler just long enough to melt cheese.  Serve sandwiches with Au jus for dipping.