Preparation: Preheat the oven to 350°. Line a full size (26" x 18") sheet pan with parchment paper and set aside.
In a large mixing bowl, whisk together the flour, baking powder, salt, black pepper, rosemary, thyme, garlic powder, and onion powder.
Add 1/2 cup of water to the flour mixture and stir with a wooden spoon to combine. Add the remaining 1/4 cup of water slowly, stopping once you've reached the ideal texture. You may not need all of it. (see photos above. The dough will feel moist, but not sticky, and there will be no dry patches. You may eventually want to switch to mixing with your hands.)
Dust a large surface area with flour and turn the dough out on to it. Knead the dough lightly for a couple minutes to help eveything come together. Shape the dough into a 1½" thick rectangle. Cover the rectangle of dough with a damp cloth and allow it to rest for 10 minutes.
Grab your rolling pin and re-dust the surface with fresh flour, adding some to your rolling pin and the surface of the dough as well. Roll the dough out into a large even rectangle, approximately the size of your large sheet pan. (26" x 18") The dough will be fairly thin.
Pick up the large sheet of dough and lay it flat over the parchment paper on the large sheet pan. Some parchment paper should still be visible on either side of the dough.
Using a brush or your hands, dampen the surface of the dough slightly with some water. Use a fork to "dock" the cracker dough, poking small holes in the surface of the dough to allow air to escape. (see photos above) Sprinkle the top of the cracker dough with some sea salt and any other seasonings you may like.
Bake the crackers for approximately 30 minutes. Begin checking them 25 minutes in, and conitnue to check them every 5 minutes, until they have developed n even brown color and are firm to the touch.
Remove the crackers from the oven. Snap them by hand into smaller pieces, and you're finished! Store these crackers in an air tight container or bag. They will keep for approximately 2 weeks stored this way at room temperature.