In a large bowl, whisk together reduced cider, sourdough starter, white sugar, brown sugar, egg, melted butter, oil, sour cream, and vanilla until smooth.
½ cup (120g) sourdough starter or discard (100% hydration), ½ cup (100g) brown sugar, ½ cup (100g) white sugar, 1 (50g) large egg, 2 Tbsp (30g) unsalted butter, melted and cooled, 2 Tbsp (30g) avocado oil, ¼ cup (60g) sour cream or full-fat Greek yogurt, 1 tsp vanilla extract
Add in the flour, baking powder, baking soda, cinnamon, nutmeg, cardamom and salt to the wet ingredients. Whisk until batter is smooth and no dry streak remain. Don't overmix!
2 cups (250g) all-purpose flour, 1 ¼ tsp baking powder, ¾ tsp baking soda, 1 ½ tsp ground cinnamon, ½ tsp ground nutmeg, ¼ tsp ground cardamom, ½ tsp salt