To make the dough, mix and knead together all of the cracker ingredients (except the seeds) to a smooth, fairly stiff dough. Add 1-2 more tablespoons of water if the dough is dry., Knead in the seeds., Let the dough rise, covered, for 60 to 90 minutes, until it's expanded a bit., Divide the dough in half. Working with one piece at a time, roll it into a rectangle approximately 14" x 9", a generous 1/8" thick. This will probably require you to roll the dough until it fights back; give it a 10-minute rest, then come back and roll some more. It may need two rest periods to allow you to roll it thin enough., For easiest handling, turn the dough onto a piece of parchment paper. Spritz the dough with water. Sprinkle with 1/4 of the topping seeds, lay a piece of parchment on top, and press the seeds in with a rolling pin. Turn the dough over, peel off the parchment, and repeat. Set the seeded crackers on a baking sheet, and repeat with the remaining piece of dough., If you don't have parchment, roll on a rolling mat or on a very lightly floured or lightly greased work surface; and transfer the seeded crackers to a lightly greased baking sheet. Sprinkle each sheet of crackers with some sea salt or flavored salt, if desired. Crush the sea salt between your fingers or grind it in a salt mill if it's very coarse., Prick the dough over with a fork, and cut it into rectangles, whatever size you like. Pull the crackers apart just a bit; you don't need to separate them completely. Let the crackers rise for 30 to 45 minutes. while you preheat your oven to 350°F; they'll get just a bit puffy., Bake for 20 minutes, until the crackers are a medium brown. Turn off the heat, wait 15 minutes, then open the oven door a couple of inches and let the crackers cool completely in the turned-off oven. When they're completely cool, break apart, if necessary, and store airtight.