Prepare all of the ingredients before beginning.
Slice the steak into thin strips. I used skirt steak.
Slice the onion and pepper into thin strips.
Clean and slice the mushrooms.
Heat 1 tbsp of butter and 1 tbsp of olive oil in a frying pan.
Add the vegetables to the pan and sprinkle with onion powder. Cook and stir until the vegetables are tender, about 3-5 minutes.
Remove the vegetables to a bowl.
Add another tablespoon of olive oil to the same frying pan you used for the veggies.
Cook the steak, sprinkling it with salt and pepper. Turn regularly, cooking until done, about 5 minutes.
Remove the cooked steak to a bowl. Wipe out the frying pan and set it aside.
Lay out your tortillas. On one half, layer steak, vegetables, and two slice of cheese. Fold the empty side over the full size.
Prepare all of the tortillas before you start frying.
Heat a tablespoon of butter in the frying pan. You may need to add more butter as you cook the quesadillas.
Place your folded, filled tortilla into the frying pan over medium high heat (I eventually had to lower it to medium).
Cook until the bottom is golden and crispy, then flip it over and do the other side. The cheese should be melted and the tortilla crispy on both sides.
Remove and repeat with the other tortillas.
These are delicious with a scoop of sour cream on the side or, as my husband prefers, with ketchup for dipping.