Mix together all the ingredients for the sourdough crackers in a bowl until a smooth dough forms.
Roll the dough out onto parchment paper that fits your baking tray until it forms a thin square, about 1/2 to 1/2 inch (1 cm). Brush the dough lightly with olive oil and sprinkle with sea salt flakes.
Using a pizza cutter or sharp knife, cut the dough into equal sized squares about 1.5 inches big. Prick dough all over with a fork to prevent it from puffing up in the oven.
Bake for 25 minutes or until lightly golden brown all over and a deeper golden brown on the edges.
Let the crackers cool completely before enjoying at room temperature. Store any extra crackers in an air tight container at room temperature.
You can use all white or all whole wheat flour if you prefer.Storing Leftovers:Cracker dough can be prepared in advance and stored in the fridge for up to 3 days before baking. This will actually intensify the sourdough flavor.Leftover crackers can be stored in an airtight container for a week or two.