NY Caramelized Onion Mushroom Pizzas with Gremolata

Steps

1. The day before, whisk the bread flour, whole wheat flour, instant yeast, sugar and 10 g of the salt (of the 12 g total; the remaining 2 g goes in the topping) in a large bowl. This dough is about 66% hydration and 2% salt.
2. Add the water and 15 g of the olive oil (of the 45 g total); mix to a shaggy dough, rest 15 minutes, then knead 8–10 minutes until smooth and elastic.
3. Divide the dough in half, shape into tight balls, place in oiled covered containers and refrigerate 18–24 hours at about 38°F (3°C).
4. Two hours before baking, set the dough balls out at about 75°F (24°C) until puffy and they spring back slowly when poked.
5. Meanwhile, heat 15 g of the olive oil in a large skillet over medium-low heat. Cook the onion with 1 g of the salt, stirring often, 25–30 minutes until deep golden and jammy.
6. Push the onion aside, raise the heat to medium-high, add the mushrooms and the remaining 1 g of salt and cook 8–10 minutes until browned and dry. Stir in the black pepper and let cool.
7. Make the rosemary oil: stir the remaining 15 g of olive oil with the rosemary and half the garlic.
8. Make the gremolata: mix the parsley, lemon zest and the remaining half of the garlic.
9. Place a pizza stone or steel on an upper-middle rack and preheat the oven to 525°F (275°C) for 45–60 minutes.
10. Dust a peel with half the cornmeal. Stretch one dough ball by hand into a thin 14-inch round with a slightly thicker rim and lay it on the peel.
11. Brush half the rosemary oil over the dough, then scatter half the mozzarella, half the onion-mushroom mix and half the parmesan.
12. Slide onto the stone and bake 8–10 minutes until the rim is deep golden, the bottom is crisp and the cheese bubbles.
13. Repeat with the remaining cornmeal, dough, rosemary oil, mozzarella, onion-mushroom mix and parmesan.
14. Scatter the gremolata over both pizzas, cool 2–3 minutes on a rack, then cut each into 6 slices.