Low-Carb Philly Steak and Cheese

I've done this two ways now, and I like the "bowl" method better.  Both are good, though:

Ingredients:
-olive oil
-half an onion, chopped
-some mushrooms
-thinly sliced roast beef
-kosher salt
-provolone cheese
-1 green pepper

1.  Heat oil in frying pan.  (It really is better to get the oil nice and hot first.)
2. Add chopped onions; saute until clear.
3.  Add chopped mushrooms; saute.
4.  Sprinkle on some kosher salt.
5.  Add thinly sliced roast beef.  (You could really use any kind of meat here- chicken, leftover roast, whatever suits you.)

Bowl:
6.  Chop up the green pepper and cook until everything is combined.
7.  Lay a few slices of provolone cheese on top, cover and turn off heat.  The cheese will melt.

Stuffed Pepper:
6.  Cut pepper in half long ways (so you get two halves to stuff off of each one.)
7.  Lay provolone cheese on the bottom of the pepper, add mixture, and put another slice on top of the pepper.  Put in oven at 395 for 15-20 mins. 

When I did the stuffed pepper method, the pepper did not soften as much as I would like before the cheese was perfect.  I thought about trying to cook the pepper a little before adding the mixture, but I decided I like the lazy way of doing it as a bowl.