Special equipment: You will need a food processor, several 10 by 14-inch baking sheets or pizza pans, a pizza cutter or a sharp knife, and a clean spray bottle.
Place the flour and salt in a food processor and process for 10 seconds to mix thoroughly. With the motor running, add the water in a steady stream, then process for 10 seconds longer. The dough should have formed into one large ball; if not, feel the dough: If it feels very sticky, add 3 to 4 tablespoons more flour and process briefly until a ball forms. If the dough feels dry and floury, start the processor again, add 2 to 3 tabespoons more water, and process until a ball of dough forms.
Once you have a ball of dough, process for 1 minute more, no longer. Turn the dough out onto a lightly floured surface and knead for 30 seconds or so. Cover with plastic wrap and let rest for 30 minutes.
Preheat the oven to 500 degrees, and place two racks near the center of the oven.
Divide the dough into 8 pieces. Work with one piece at a time, leaving the other pieces covered. On a lightly floured surface, with lightly floured hands, flatten a piece of dough with your palms. Then roll it out to a very thin rectangle or round, as even a thinness as possible to ensure even cooking. Gently lift the dough from your rollling surface and place it on a large baking sheet or pizza pan. Sprinkle on one of the optional toppings or leave plain. Using a knife or a pizza cutter, cut through the dough to make rectangular crackers. (Don't worry if they are not all exactly the same size. Variations in size and flavor will make your crackers interesting.) Spray the dough lightly with water and place on the upper oven rack.
Begin rolling out the next piece of dough, keeping an eye on the crackers already baking. (Crackers brown from underneath.) Check on them 2 1/2 to 3 minutes after they go in. As soon as the thinnest patches of the dough have started to brown, take them out. If necessary, continue baking, checking every 30 seconds, but it is better to take the crackers out a little early than too late.
You will soon get a feel for timing and degree of doneness. Variables that affect timing are the heat of your oven and how thin you managed to roll out your dough. When they come out of the oven, some of the crackers will be crisp, while others will need a little time in the air to crisp up. Transfer to a large bowl, breaking up any incompletely separated crackers. Roll out the remaining dough, season, and bake. When completely cool, crackers can be stored in a well-sealed plastic bag or cookie tins for up to a month.