Heat a grill to medium heat. Brush zucchini with olive oil on both sides and sprinkle with salt. Carefully grill slices for 2 to 3 minutes per side, flipping once. Reserve.
Slowly and carefully stretch each dough ball into a 12-inch round (or puzzle piece or US state…). Stack on well-floured sheets of wax paper.
When your fire and grate are ready you should be able to hold your hand over about 3 inches above the grate for 3 to 4 seconds. Transfer thinned dough onto oiled grill grate one at a time. Let cook for 1 minute. Using a metal spatula, flip pizza on top other side.
Layer toppings on pizza crust – about one-third zucchini, sliced onions, queso fresco and cilantro. Tent or close grill cover, allowing to cook for 4 to 5 minutes or until cheese is melted.
Transfer to a baking sheet or cutting board, cut and serve immediately. Alternatively, you can keep pizzas warm on a cooler part of the grill or in an oven set at 200 degrees until ready to serve.