Pre-measure all of the ingredients.
In a bowl, add the water and the sourdough starter or the dried yeast. Mix well until all the sourdough dissolves.
Add half of the flour and mix until you form a very wet dough.
Add the other half of the flour and mix well for another 2 minutes.
Add the salt and knead the dough using your hand for 7-8 minutes.
Cover the bowl and let the dough rest for 2 hours.
Complete one set of Stretch & Fold.
After 2 hours of resting, sprinkle flour on the top of the dough and your work surface.
Gently turn the bowl upside down to release the dough onto the floured work surface.
Gently stretch the dough into a rectangle and sprinkle ⅔ of the seeds and crushed walnuts evenly.
Fold the dough back on itself and form it into a round shape. Let it rest for 30 minutes.
Line the tin with baking paper.
After 30 minutes, form the dough into a long egg shape and transfer it into the tin with the seam side down.
Lightly brush the top of the bread with water and top with the remaining seeds and crushed walnuts.
Cover the dough and let it prove until it has almost doubled in size.
Bake at 180°C (fan) for 30-40 minutes, or until golden brown.
Let the bread cool down on a cooling rack for at least 2 hours before enjoying.
