Preheat oven to 450 degrees. Place a pizza stone or heavy baking sheet in oven while it preheats.

In a large bowl, whisk together flour, seeds, baking powder, and salt. Add the water and oil and stir until just combined. Turn dough onto a work surface and knead 4-5 times, just to bring it together.

Divide dough into 3 portions. Roll one portion on parchment paper until very, very thin - dough will be about 10 inches in diameter. Brush the top of the dough very lightly with olive oil, then sprinke with sea salt. Using a baking peel or a unrimmed cookie sheet, slide the parchment with the rolled dough onto the preheated pizza stone or baking sheet. Bake for 8-10 minutes, or until golden. Use your "peel" (makeshift or otherwise) to remove cracker from the oven. Transfer to a cooling rack to cool before breaking into pieces. Repeat with the other two portions of dough.

Store in an airtight container for 2-3 days.