-
1
Place all ingredients in a medium bowl and mix to combine.
-
2
Season with freshly ground black pepper and set aside.
-
3
Place a fine mesh strainer over a medium bowl and put red peppers, artichokes, and pepperoncini in the strainer.
-
4
Press lightly on the vegetables to extract any liquid; set aside.
-
5
Heat oil in a large frying pan over medium-high heat until shimmering.
-
6
Place mushrooms in the pan and season with salt and freshly ground black pepper.
-
7
Cook, undisturbed, until mushrooms are golden brown on the bottom, about 3 minutes.
-
8
Flip and cook until mushrooms are soft and golden brown on the other side, about 4 minutes more.
-
9
Drizzle vinegar over mushrooms and cook until vinegar has been absorbed, about 1 minute.
-
10
Remove from heat and set aside.
-
11
Lay the bottom half of the bread on a clean work surface and evenly distribute all of the reserved olive salad.
-
12
Spread mushrooms evenly over olive salad and top with cheese slices.
-
13
Press lightly on the reserved red peppers, artichokes, and pepperoncini in the strainer to extract any additional liquid, then distribute evenly over the cheese.
-
14
Cover with top half of the bread and press down firmly to compact the sandwich.
-
15
Slice into 4 to 6 sections and serve.
