Philly Cheese Steak Sliders

olive oil

medium onion (sliced)

medium green (or red) bell pepper (sliced)

sliced mushrooms

finely chopped fresh oregano ((or 1 tsp. dried oregano leaves))

Sea salt (or Himalayan salt) and ground black pepper ((to taste; optional))

raw lean beef sirloin (sliced very thin)

sliced banana (or cherry) peppers ((optional))

thinly sliced provolone cheese

small whole wheat rolls, split, toasted