Preheat and Prepare: Set your oven to 420°F (215°C). While it warms up, line a baking sheet with foil and prepare a sheet of parchment paper lightly dusted with flour for the dough.
Bring Dough to Room Temperature: Place the pizza dough on the floured parchment paper and allow it to rest uncovered for 30–60 minutes. This makes the dough soft, elastic, and easier to stretch.
Roast the Tomatoes: On the prepared baking sheet, toss halved grape tomatoes with olive oil and oregano. Spread them evenly and roast in the oven for about 8 minutes, until they soften and release some of their natural juices. Set aside to cool slightly.
Prebake the Flatbread Base: Stretch the dough gently with your hands or a rolling pin to your desired thickness. Transfer it (still on the parchment paper) to the oven and bake for 12 minutes, until the surface begins to firm up and lightly golden edges form.
Add the Toppings: Remove the base from the oven and spread the pesto evenly over the crust. Scatter roasted tomatoes, chopped peperoncini peppers, and thinly sliced red onion on top. Return the flatbread to the oven and bake for an additional 5 minutes, allowing the toppings to warm through and flavors to meld.
Finish and Serve: Take the flatbread out of the oven and top it with fresh arugula. Grind some black pepper over the top for a finishing touch. Slice and serve immediately while warm.
