This southern French tart takes its name from pissala, a pungent anchovy paste that gives the flatbread its distinctive flavor. Serve this savory bread as an appetizer or snack with chilled rosé.
1 (¼-oz.) package active dry yeast
3 cups flour
¾ cup extra-virgin olive oil, plus more for greasing
1 tbsp. kosher salt, plus more to taste
20 oil-packed anchovies, drained and finely chopped
12 medium yellow onions, thinly sliced lengthwise
4 sprigs thyme
2 sprigs rosemary
2 bay leaves
Freshly ground black pepper, to taste
½ cup pitted, halved black olives
1. Make the dough: Whisk together yeast and 1 cup water, heated to 115°, in a large bowl; let sit until foamy, about 10 minutes. Add flour, ¼ cup oil, and salt, and stir until dough forms; transfer to a floured work surface and knead until smooth, about 6 minutes. Transfer to a greased bowl, cover with plastic wrap, and let sit until doubled in size, about 1 hour.
2. Meanwhile, make the topping: Heat remaining oil in a 6-qt. saucepan over medium-low heat; add anchovies, and cook, stirring, until dissolved in the oil, about 7 minutes. Add onions, thyme, rosemary, bay leaves, and salt and pepper, and cook, covered and stirring occasionally, until reduced and softened, about 1 hour; uncover and cook, stirring occasionally, until liquid evaporates and onions are golden brown, about 30 minutes. Remove from heat and discard herb sprigs and bay leaf; let cool.
3. Heat oven to 425°. Uncover dough and transfer to a work surface; using a rolling pin, roll dough into a 12" x 18" rectangle. Transfer dough rectangle to a greased 13" x 18" rimmed baking sheet, and then cover evenly with onion mixture; place olive halves decoratively over onion mixture. Cover tart loosely with plastic wrap and let sit until dough is puffed, about 1 hour. Bake until golden brown at the edges, about 20 minutes. Let cool for 10 minutes before cutting into squares to serve.