To a medium bowl, add the sourdough starter and melted butter. Stir to combine well.
Add the flour and mix until all the flour is absorbed. You may may have to knead gently to get it combined.
Cover the bowl with plastic wrap or a dishtowel. Place on the countertop overnight.
The next morning, place the dough on a countertop lightly dusted with flour to prevent sticking.
Bread apart the dough and add the salt and baking soda.
Add any seasoning mix you like. Work the ingredients evenly into the dough.
Divide the dough into quarters. Place 1/4 of the dough onto a sheet of parchment paper. Using a rolling pin, roll the dough as thinly as possible. Repeat this step until all the dough is rolled out.
Using a pizza cutter or sharp knife, cut the crackers into your desired shape.
Place the parchment paper on a baking sheet. Sprinkle with sea salt.
Bake in a preheated 350-degree oven for 15-20 minutes until they reach the desired crispness.