Mushroom Open-Faced Sliders

From a distance, these open-faced sliders look a lot like a little hamburger! But with a closer look you'll see that this fun app is light, summery and delicious. To be honest, I wasn't much of a mushroom fan but when sauteed with onions and peppers, I changed my mind!
                                                                                                   
Ingredients:

Portobello Mushrooms--- 1/2 Lb.
Sourdough Bread--- 1 Loaf
Onion (sliced)--- 1/2 C
Bell Pepper (sliced)--- 1/2 C
Tomato--- 1 Large
Parmesan Cheese (grated)--- To Taste
Olive Oil--- 2 Tb
                                                                                                   
Prep by slicing onions, peppers and tomatoes. In a large frying pan, saute onion and pepper on a low heat until they are fully tender. Remove veggies and set aside.

Cut thick slices of bread and oil both sides. Add bread and mushrooms to pan- keep an eye on the bread and flip once they are toasted.

 Saute mushrooms until tender- you'll see they tend to flatten out like a burger patty. 

Once bread is toasted, remove from pan and top with veggies, mushrooms and grated parmesan cheese.