Panuozzo (Neapolitan Pizza Sandwich)

Steps

1. In a large bowl, combine the tipo 00 flour and the instant yeast. Pour in the room temperature water, 68 to 77°F (20 to 25°C), and stir by hand or with a spatula until no dry flour remains. Cover and let rest for 15 minutes.
2. Add the salt and 1 tablespoon of olive oil, then knead for 10 minutes by hand on the counter, or 7 minutes in a stand mixer on low speed. The dough should become smooth, supple, and barely sticky; stretched between your fingers, it should form a thin membrane without tearing.
3. Shape it into a ball, set it in the lightly oiled bowl, cover, and let it rise for 2 hours at 72 to 75°F (22 to 24°C), until nearly doubled.
4. Divide the dough into 4 pieces of about 7 1/2 oz (210 g). Round each one by tucking the edges underneath to tighten the surface, then roll it into a 6 inch (15 cm) log. Set them on a tray dusted with semolina, cover with a towel, and let rise for 1 1/2 to 2 hours, until puffy and a gentle fingertip press leaves a slight dent.
5. At least 45 minutes before baking, set a pizza stone, baking steel, or upside-down sheet pan in the upper third of the oven and preheat to 525°F (275°C), or as high as your oven goes (at least 480°F, 250°C).
6. On a semolina-dusted counter, press one piece of dough with your fingertips into a long oval about 11 x 4 inches (28 x 10 cm) and 1/2 inch (1.5 cm) thick, leaving a slightly thicker rim all around. Do not use a rolling pin: it would knock out the bubbles that make the bread puff. Brush the top with a little olive oil.
7. Slide two panuozzi onto the stone and bake for 8 to 10 minutes, until well puffed, golden, spotted brown underneath, and hollow sounding when you tap the bottom. Repeat with the remaining two.
8. Let cool for 2 minutes, then split each loaf horizontally with a bread knife, leaving one long side attached like a hinge.
9. Slice the provola, lay it over the bottom of each open loaf, and return them to the oven for 2 to 3 minutes, until the cheese melts and the cut edges toast.
10. Spread pesto on the inside of the top half. Drape the mortadella in loose folds over the melted provola, then add the arugula tossed with the remaining olive oil. Close, press gently, cut each panuozzo in half on the diagonal, and serve right away.