Preheat your oven to 320F/160C. Ensuring the oven is at a stable temperature before the tray enters is vital for immediate moisture evaporation.

Add the sourdough starter, honey, vanilla and coconut oil together in a bowl. Mix with a spoon until they are well combined. You are looking for a homogenous emulsion where the oil is fully integrated into the starter.

Once the liquid ingredients are smooth, add the oats, nuts and spices. Stir the ingredients until everything is well coated with the sourdough starter mixture. Every surface area must be covered to ensure even browning and consistent clumping.

Press a tight layer of granola onto a baking tray lined with baking paper. Don't leave any gaps. This compression is the physical mechanism that initiates the clumping action while baking, minimizing air pockets that lead to burning. If you prefer loose clusters, press firmly but leave some texture on the surface. If you wish to create a block that can be cut into sourdough granola bars later, press very firmly and evenly with a flat object until the surface is level.

Bake low and slow until the mixture is lightly toasted. The granola will take around 20 minutes to toast. Keep an eye on it as the honey will cause it to burn easily. You are looking for a uniform pale amber color.

Once cooled, break the granola up into pieces and toss through the dried fruit if using. Do not attempt to break the granola while it is warm, as the sugars have not yet fully crystallized.

Store the granola in an air tight container. A glass jar is best for maintaining the crispness of the oats and preventing moisture absorption from the air.