1. The recipe for those who have a sourdough starter stashed away in the fridge – any wheat starter will do, at about 100% hydration so fairly sloppy. If you need to make it up first, here’s the recipe for the San Francisco starter, and this is the Tartine starter.
2. Refresh the starter, if you need to, on the day you make the sponge, but at least 8 hours earlier. Possible timing guidelines:
- Day 1 midday – refresh starter
- Day 1 night – make the sponge
- Day 2 – make the main dough and bake
3. For the sponge, mix all the sponge ingredients in a large bowl with a hand whisk. Cover with a damp cloth and leave at room temperature overnight. It should get seriously bubbling.
4. Transfer the sponge to a standing mixer bowl (or use a hand-held mixer) with a paddle attachment. Add half the flour and beat for a couple of minutes on low speed, then for further 8-10 minutes on medium speed. Add the rest of the flour, the grains and flakes and the salt and beat with a dough hook attachment, or knead by hand, until the dough is stretchy, elastic and smooth and doesn’t stick to your hands or the sides of the bowl.
5. Tip it into a lightly greased large shallow bowl or a plastic container. Cover and leave in a warm place for an hour. After that time grab the underside of the dough with oiled hands, stretch and fold it in three like and envelope and then in three in the opposite direction. Cover and keep warm for another hour.
6. Repeat the stretching and folding twice more, on the hour. After the final rise turn it out onto the floured surface and divide into 8 pieces, about 100g each. Shape each loosely into a round and leave covered with a towel for 20 minutes.
7. Line a large baking sheet with parchment. Shape the rolls into tight balls or oblong batards and place on the sheet, well-spaced out. Using a chopstick or a thin wooden spoon handle, make a deep trench across each roll going all the way down but making sure not to split them.
8. Cover with cling film and prove in a warm place for an hour, until risen by half. Alternatively, refrigerate overnight and bake the next morning having brought them back to room temperature (about 3 hours) – that will deepen the flavour.
9. Preheat the oven to 220C/450F/gas 8. Place another baking dish at the bottom of the oven, or prepare a spray bottle.
10. Transfer the risen rolls into the oven, throw a very wet cloth onto the bottom tray or spray the inside of the oven with water and close it immediately. Bake the rolls for 15 - 20 minutes until very lightly golden.