Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

Whisk together the flour, cocoa powder, and baking soda in a bowl; set aside.

Combine the sourdough starter, sugar, vegetable oil, egg, and red food coloring in another bowl until smooth.

Mix in the dry ingredients gradually, until just combined.

Scoop rounded tablespoons of dough onto the prepared sheets, leaving enough space between each cookie.

Bake for 12-15 minutes until the edges are set but the centers look slightly underbaked.