This whole process takes up to a day starting after breakfast- but you'll see it fits nicely round whatever you need to get up to & the timings are quite forgiving. If you want, you can start step 1 the night before, in which case put the bowl of sour in the fridge to develop overnight.
Step 1: First you need to make the sour
150g sourdough starter
400g strong white flour- pick your favourite from the Shipton collection- I like the Canadian, Italian or Organic no4
400ml warm water
Mix together in a large bowl, cover with a shower cap or wet tea towel & leave to develop for 3-4 hours in a warm room. How long depends on the room temperature but it should have the consistency of paste when you start & be a looser, bubbly mixture when you're ready for step 2.
Step 2: make the dough
900g of the sour
400g of the same strong white flour as before
100g of your favourite wholemeal flour from the Shipton collection- I like the Swiss dark, or Emmer. Spelt also good.
200ml warm water
8g brown sugar
Before making the dough, take out 50g from the sour & mix with 50g of the strong white flour you are using & 50mls of water. Put in a sealed plastic pot with some holes in the lid & leave in the bottom of the fridge- this is your starter for the next round of bread baking. It will last happily for a week in the fridge- if you don't plan to use it then just discard 2/3rds (100g) and add fresh 50g of white flour & 50mls of water.
To make the dough mix the remaining sour with the rest of the ingredients & need for 10 minutes. This dough should be elastic when ready- like Blutak. Put in a large oiled bowl, cover & leave to rise for 3-4 hrs. Then Step 3- knocking back & 2nd prove.
Step 3: knock back & 2nd prove
Tip out the dough & lightly knock back. Then separate in to 2 (~800g each), if I'm feeling adventurous this is where I add eg 80g walnuts to a loaf, then shape each in to a ball & place in to oiled bowls with the seams upwards. Leave to rise for 1-2 hours. I find that if this 2nd prove is too long, then the loaf spreads out too much- still tastes great but doesn't look as good.
Step 4: baking
Heat the oven to 230C with the baking tray in. When up to heat, take out the baking tray, dust with flour & tip out the loaves. Quickly slash with a sharp knife with your signature mark, then put in the oven, add some cold water to a tray at the bottom to create steam, and bake for 40 mins. Take out & cool on a rack. Eat with real tasty butter. Freshly baked tastes a bit like crumpets, as the loaf matures it is great toasted. You'll need a good bread knife!
Tips about the sourdough starter
If you don't have a sourdough starter- ask a friend to give you some of their's. Or simply make it yourself by adding 50ml water to 50g white flour in a sealed pot with a lid that has holes in it. Leave on your kitchen top, then remove all but 50g each day & adding 50g flour, 50ml water. Keep doing that for a few days until a nice bubbly mixture is generated & you are ready for step 1.
Lots of nonsense is written about starters & the pressure of looking after them (sourdough starter hotels in Stockholm etc). It's really not a lot of hassle. If you go away you can put the sourdough starter in the freezer then de-frost & give it a couple of cycles of feeding to get it vigorous again. Likewise if you forget to feed it, don't worry- feed it again as soon as you remember. If a lot of liquid forms on the top of the starter- tip that away before feeding.
If it doesn't look very vigorous, give it a couple of rounds daily feeding, leaving it our your kitchen surface during the day to get it going again.
I'm told if the starter goes black or is foul smelling, then clearly something's gone wrong & you should through away & start again. This has never happened to mine.