mixed starter and flour, autolysed for 30mins to 1 hour. french fold for 3 mins. add salt and french fold for 3 mins. rest for 30 mins. add in sweet potato and walnuts. leave for 3 hours. shape into boule let proof for 1 and half hours or retard in the fridge overnight. baked at 450 F for 20mins in a dutch oven. further baked for 10mins after removing the cover.