The Provencal pissaladiere is an oven-baked (pizza-like) focaccia or torta topped with caramelized onions, black Nicoise olives, and anchovies. A street food of Nice, it is often sold by street vendors or at local markets. It can also be served as an appetizer. It is believed to have been introduced to the area by Roman cooks during the time of the Avignon Papacy. The dough in this recipe rises for 1 to 1 1/2 hours. If a longer or overnight rise is more convenient, make the dough with 1/2 teaspoon of instant yeast and let it rise in the refrigerator for 16 to 24 hours. The caramelized onions can also be made a day ahead and refrigerated. Recipe requires use of a baking stone.