How to Make It
In a large bowl, mix 2 cups flour, baking powder, and 1/2 teaspoon salt. Add 2/3 cup water and the oil and mix just until dough comes together. Scrape onto a lightly floured board and knead two or three turns. Divide dough into thirds; shape each portion into a ball, flatten slightly, and cover loosely with plastic wrap. Let rest 20 minutes.
One at a time, with a lightly floured rolling pin, roll each portion into a rectangle about 1/16 inch thick. Using a lightly floured knife, cut rectangle into 2-inch squares (discard uneven edge pieces if desired). With a wide spatula, transfer squares to buttered or cooking parchment-lined 12- by 15-inch baking sheets, spacing squares slightly apart.
Brush tops lightly with egg white (discard any remaining) and sprinkle evenly with sesame seeds and remaining 1/2 teaspoon salt. Pierce each square with the tines of a fork to make several rows of indentations.
Bake in a 300° regular or convection oven until light golden brown, 20 to 25 minutes; if baking more than one sheet at a time in one oven, switch their positions halfway through baking. Transfer crackers to a rack to cool completely.
Nutritional analysis per cracker.