Preheat oven to 450°. Roll the dough into an 11 x 15 inch rectangle and place it on a lightly oiled baking sheet. Prick the dough all over with a fork. In a small bowl, combine the water, 1 tablespoon of salt and 2 tablespoons of the oil; brush over the dough. Let the dough rise for about 30 minutes. 2. In a large, heavy skillet, combine the remaining 3 tablespoons of oil with onions, garlic, bouquet garni, and 1 teaspoon salt. Sweat, covered, over low heat until the onions are soft and cooked through, about 30 minutes; they should not brown. Discard the bouquet garni and spread the onion mixture evenly over the bread dough.
Bake the pissaladière in the center of the oven until evenly browned and crisp, about 20 minutes. (Be careful not to burn the onions. Reduce the oven temperature if necessary.) Remove from the oven and arrange the olives and anchovies in an even pattern over the onions. Sprinkle with thyme. Serve warm or at room temperature, cut into rectangles.