Gather your ingredients so that you have everything close at hand on the counter or table.
Make the Cracker Dough
In a medium bowl, combine the all-purpose flour, kosher salt, sourdough starter, and extra-virgin olive oil. Also add in any seasonings at this time, if you choose to do so. Mix together with a fork until dough comes together.
Knead by hand 7-10 times, until dough becomes smooth.
Cover with plastic wrap and refrigerate for 30 minutes or more, for the dough to become firm.
Form the Crackers
When ready to make the crackers, preheat oven to 350 degrees. Divide dough in half. Working with one piece at a time, press dough out by hand or rolling pin to flatten.
At this point, you may either roll out the dough with a rolling pin on a lightly floured surface until dough is very thin.
Or you may opt to use a pasta roller, which is the method I've found that works very well to make a crispy, thin, cracker.
It may also be necessary to lightly flour the piece of dough before you begin to roll it. Sometimes, my dough needs it, other times it does not. Using a pasta roller, I begin rolling out the dough at #2 and continue until I reach #4 in thickness. I also cut the length of dough in half midway through the process, which is a good length to fit the baking sheet.
Place the thin sheets of dough on an ungreased baking sheet. (I've read recipes that place the sheets of dough on parchment paper, and this works as well, but I've found that it isn't necessary.) Repeat with remaining piece of dough.
Lightly smooth a little olive oil over the dough with your fingers. I've also used water instead of the oil, but the salt seems to stick to the oil a little better. Sprinkle sea salt over the dough.
Bake and Break the Crackers
Bake the dough in a preheated oven for 10-12 minutes until edges begin to brown, turning the pan halfway through the baking period to help the crackers cook evenly.
Remove from oven and transfer to a wire cooling rack. When cool, break into bite-size pieces and store in an airtight container or plastic bag for up to a week. This recipe will fill two baking sheets or make about 40-50 crackers.