Filling Phillys

Sometimes I don't feel like spending a lot of time making a big dinner, so these hearty and delicious sandwiches are one of my go-to quick dinners.  

1 large onion
2 green bell peppers
1 lb deli roast beef
Swiss cheese slices
Ciabatta buns
1 envelope McCormick Au Jus gravy mix, prepared per directions but use less water to make it thicker and tastier.
Chips
 
Slice the onion and peppers and saute in butter (I use I can't believe its not butter) until onions are caramelized and peppers are cooked.  Toast the buns in the oven (350 degrees for 5 min works for me)  Add the roast beef and warm thoroughly.   Placed a slice of swiss cheese on the toasted bun then load up with some meat and veggies.  Serve hot with au jus and chips.