Make rosemary oil - Not mandatory, but highly recommended. See notes for directions - this can be done ahead of time.

Remove pizza dough from fridge 30 minutes before starting. Have ingredients pre-measured and ready to go.

Place sliced potatoes into a medium bowl of water and soak for a few minutes. Swish them around with your hand a bit. Drain and repeat. Place potato slices and a teaspoon of salt into a medium pot and cover with clean cold water. Bring to a simmer (not a boil) and cook for 2 - 3 minutes. Do not cook all the way through, just enough to soften. If you cook them too much, they will fall apart. (You can also cook the onions with the potatoes to soften them if you like.)

Drain the potatoes and rinse with cold water. Place on clean kitchen towel (not a linty one) or paper towel, pat dry.

Preheat grill to 500°F // 250°C.

On a lightly floured surface, stretch (or roll out with a floured rolling pin) both balls of pizza dough to about a 14 inch (35cm) round or square. It doesn't have to be perfect, mine never are, just get as close as you can. Turn a large sheet pan upside down and place dough on the bottom of the pan (baking sheet). *See notes for using cornmeal.

Gently place dough directly onto clean grill grates. Lower lid and cook for 2 - 3 minutes without disturbing. Depending on the size of your grill, you may have to do them one at a time. Lift the lid and use tongs to lift dough and check under the edge for doneness. You want a light brown crust with a few char spots, but not totally cooked through.

Remove the dough from the grill and flip over. Place on a sheet pan to cool slightly.

While dough is cooling, toss par-cooked potato slices, sliced onion, 2 tbsp. rosemary, 1/2 cup olive oil (or infused olive oil if you did the extra credit), plus salt and pepper to taste, into a medium mixing bowl. Toss to combine, making sure to separate slices of potato and coat each one.

Spread half of the ricotta over the grilled side of each pizza. Top with potato and onion mixture - go close to the edge, covering the crust will keep it from burning. Shingle the potatoes so they cook evenly and top with any bits of rosemary or onion left in the bowl.

Return the pizza to the grill. Lower grill temperature to 400°F / 200°C and cook for 5 - 6 minutes with the top closed, rotating pizzas halfway through to ensure even cooking, or until potatoes are cooked through. If crust is getting too brown, shut off one burner and slide pizza over that burner, so there is no direct heat underneath it. (*Everyone's grill is different. You may need to reduce the heat even more if your dough is browning too much. Knowing where your grill's hotspots are is helpful.)

Remove pizza from grill and top with grated Pecorino Romano cheese and flaky sea salt before serving.