For the levain,
100g of activated starter click here for recipe
50g of Strong White flour
50g of Strong whole wheat flour
100g of water.
For the main dough,
All of the ferment
400g of Strong White flour
200g of Strong whole wheat flour
300g of Walnuts
350g of water
14g of salt.
Make up the levain by adding the activated starter to the other levain ingredients, leave covered for 6 to 8 hours until the surface is showing good signs of fermentation (lots of bubbles and the surface caving in on itself forming creases).
Add all the main dough ingredients apart from the walnuts and salt to the levain, mixing together on a slow speed if you are using a mixer or knead together for only a minute or two to form a cohesive mass if you are making by hand. Leave covered overnight.
Toast the walnuts in a hot oven 200C for 5 to 8 minutes, once they are cool, add the walnuts and the salt to the main dough and mix to fully incorporate. Leave the dough to rise, stretching and folding the dough every hour for 3 to 4 hours or until the dough has developed good elasticity. You should find that at the beginning the dough is very soft but after the stretching and folding has been carried out a few times, the dough should show signs of tightening up more. Walnuts will break up and pop out of the dough as you work, this is not a problem, simply work them back into the dough. Be careful to avoid deflating the dough any more than you have to during this process.
When the dough has developed sufficiently, the gluten allows the dough to be stretched and at the same time the elasticity is stronger, form the dough into two equal pieces. Take each piece and form a long baton shape then finally twist each baton several times, this merely gives the finished loaf an attractive log like finish.
Leave the loaves to rise for an hour on a baking sheet before placing in a hot oven 220C for 30 to 35 minutes.
I use walnut halves, these seem to allow for a certain amount of breaking up into smaller pieces during the mixing in, in my food mixer but it's entirely possible to use broken walnut pieces for this bread
I have said before that my house is cold, I live in Norfolk and I try to avoid using the heating as much as possible, choosing instead to put on sweaters, If you are baking bread in really warm parts of the world, then do take into account the fermentation of both the levain and the main dough will take less time.