Preheat your oven to 350°F (175°C).
In a large bowl, cream together butter, brown sugar, and granulated sugar until smooth.
Beat in the egg and vanilla extract until well combined.
Stir in the sourdough starter until fully incorporated.
In a separate bowl, whisk together flour, baking soda, and salt.
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Fold in the chocolate chips.
Drop tablespoon-sized balls of dough onto a parchment-lined baking sheet.
Bake for 10-12 minutes, or until edges are golden brown.
Let cookies cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.