Mix together the sourdough starter, flour, salt, butter, and herbs to make a smooth (not sticky), cohesive dough.

, Divide the dough in half, and shape each half into a small rectangular slab. Cover with plastic wrap, and refrigerate for 30 minutes, or up to a couple of hours, until the dough is firm.

, Preheat the oven to 350°F., Working with one piece of dough at a time, very lightly flour a piece of parchment, your rolling pin, and the top of the dough., Place the dough onto the floured parchment and roll it about 1/16" thick. It'll have ragged, uneven edges; that's OK. Just try to make it as even as possible.

, Transfer the dough and parchment together onto a baking sheet. Lightly brush with oil and then sprinkle the salt over the top of the crackers.

, Cut the dough into 1 ¼" squares; a rolling pizza wheel works well here.

, Prick (dock) each cracker a couple of times with a fork; this will help keep them from puffing up like little pitas as they bake.

, Roll and cut the second piece of dough following the directions above. , Bake the crackers for 20 to 25 minutes, until they're starting to brown around the edges. Midway through, rotate the baking sheets both top to bottom and front to back; this will help the crackers brown evenly., When fully browned, remove the crackers from the oven and place the pans on a rack to cool.

, Store crackers, well wrapped, at room temperature for up to a week; freeze for longer storage.