In a large bowl, I combine the sourdough starter, flour, salt, softened butter, and herbs if I'm using them. I mix it just until everything comes together into a smooth, cohesive dough that isn't sticky. It only takes a couple of minutes by hand, no fancy equipment needed here at all.
Once the dough is formed, I divide it in half and shape each portion into a small rectangular slab. I wrap them in plastic and pop them in the fridge for about 30 minutes. This firms things up, which makes the rolling stage so much easier to manage.
Working with one piece at a time, I lightly flour a sheet of parchment, my rolling pin, and the top of the dough. I roll it out to about 1/16 inch thick, which feels almost paper-thin. The edges will look ragged and uneven, but that's completely normal and part of the charm.
I transfer the rolled dough, still on its parchment, onto a baking sheet. Then I brush it lightly with oil and sprinkle on coarse salt. Using a pizza cutter, I slice the dough into small 1 1/4 inch squares, which bake up into perfect bite-sized crackers.
Before baking, I prick each square a few times with a fork so they lay flat instead of bubbling up in the oven. I bake them at 350°F for 20 to 25 minutes, rotating the pans halfway through so everything browns evenly.
Once they're golden around the edges, I pull the pans out and let the crackers cool completely on a rack. This final cooling step is what locks in that satisfying crunch, so try not to skip it even if you're impatient like me.