Make the dough: In a large bowl, whisk together the flour, salt and instant yeast. Add the water. Using a rubber spatula, mix until the liquid is absorbed and the ingredients form a sticky dough ball. Cover the bowl with a damp cotton towel or plastic wrap. Set aside in a warm spot to rise for about 1 1/2 hours, until the dough has doubled in volume.

For the pissaladière toppings: In a large sauté pan, heat 1 tablespoon olive oil over high heat. When it begins to shimmer, add the onions and a pinch of salt. Immediately reduce the heat to medium-low and cook, stirring every few minutes, until the onions are lightly golden, about 15 minutes.

Meanwhile, in a food processor, mince the garlic and anchovies together. Add 2 tablespoons of oil and blend until smooth. Add the capers and pulse to coarsely chop. Add the olives and pulse again to coarsely chop. Set aside.

Set a rack in the middle of the oven and preheat it to 425°F. Line a 13" by 18" rimmed sheet pan with parchment paper. Pour the remaining 3 tablespoons oil on the prepared sheet pan. Using two forks, deflate the dough by releasing it from the sides of the bowl pulling it toward the center. Rotate the bowl quarter turns as you deflate, turning the mass into a rough ball. Use the forks to lift the dough onto the oil on the prepared sheet. Roll the dough ball in the oil to coat it all over. Let it rest uncovered, without touching it, for 20 minutes.

With lightly greased hands, press down on the dough, using all 10 fingers to dimple and stretch the dough outward. Pull gently on the ends and stretch them toward the corners of the sheet pan. If the dough begins to resist being stretched, let it rest for 5 minutes, then stretch it again, continuing until it fits most of the sheet pan.

Spread the anchovy puree over the surface of the dough, followed by the sautéed onions then the olives and tomatoes. Use all 10 fingers again to dimple the dough and gently stretch it.

Transfer the sheet pan to the oven and bake for 25 to 30 minutes, until the underside is golden and crisp. Remove the pissaladière from the oven and when cool enough to handle, transfer it to a cutting board. Let it cool for 10 minutes before cutting it into squares or strips.