In a medium bowl, combine the flour, sourdough starter, butter and salt. Start by using a wooden spoon, then use your hands to work the dough into a ball. It will start out messy, but once the ingredients blend, it will be a soft and pliable dough. Flatten the ball into a rectangular disc, a visual example would be like the lid of a small shoebox.
Using two sheets of parchment paper, sandwich the cracker dough between the sheets. I put a tea towel or silpat mat under the bottom layer to prevent it from slipping. Roll the dough with a rolling pin until it is about 1/16 of an inch thick. It will nearly touch the edges of then parchment paper when it is thin enough. Thicker crackers will take longer to bake and could burn on the edges while remaining slightly doughy in the middle.
Preheat the oven to 350°. Prepare the dough by removing then top layer of parchment and drizzling the top of the dough with olive oil. Smooth the olive oil over the entire surface. I use my hands for this step! Cut the crackers into one inch squares using a knife, small cookie cutter, pizza cutter, or pastry wheel. Leave the dough exactly as it is, do not try to separate the crackers. Sprinkle the crackers with coarse salt, pepper and any additional seasonings you desire. Garlic power, everything bagel seasoning, parmesan cheese, flaky sea salt, or poppy seeds are all great options for more flavoring.
Bake the crackers for 25-30 minutes. Once they are fully cooked, transfer the crackers to a cooling rack. Do not leave them on the parchment paper to cool, this will cause the bottoms to be soggy.
Store the fully cooled crackers in an airtight glass container. They will start to go stale after about three days, but don’t worry! These savory crackers won’t last that long.