Prepare the sourdough on day 1 by combining the sourdough ingredients in a medium bowl. Mix well, cover and leave to rest at room temperature for around 12 hours.
On day 2, dry-roast the Austrian pumpkin seeds in a frying pan until they start to pop and smell nutty.
Combine 310g of the sourdough starter (the rest goes back into the fridge for future bakes) and the main dough ingredients - with the exception of the pumpkin seeds - in a large bowl.
Knead for about 10 minutes, then add the pumpkin seeds.
Work in the seeds until evenly distributed.
Place the dough back into the bowl, cover and leave to rest for an hour or two until the dough has risen visibly.
Punch down the dough, shape into a round, flour the surface and place face-down into a pre-floured proving basket.
Preheat the oven to 220°C half an hour before baking. If you use a La Cloche baking dome, preheat this in the oven from cold.
Once fully proved (after several hours in my kitchen but this will depend on the temperature in your room), turn out the bread from the proving basket onto the hot La Cloche plate.
Put the La Cloche cover back on and bake for 10 minutes at 220°C, then turn down the heat to 190°C for another 40 minutes. Take off the La Cloche for the last 10 to 15 minutes.
Cool on a wire rack.