Make your leaven by following the instructions on my Overnight Sourdough Bread recipe up to the beginning of step 4. When making focaccia, I use 1kg of flour and make 2 additional normal loaves. But for this recipe, I will walk through making just one focaccia loaf.
With 75g of leaven ready to use, add it to a large bowl along with 200ml of warm water and mix thoroughly. To this add 350g of white bread flour. At this stage, mix the dough to a dry, shaggy consistency. Cover and leave for 30 minutes.
After 30 minutes, add in another 25ml of warm water and mix until well combined. Cover and leave for 15-20 minutes. Then add the final 25ml of warm water along with the teaspoon of fine sea salt. Re-cover and leave for 15-20 minutes.
You now want to start your 'stretch and fold' your dough. Lift up the dough in the middle until the ends fold in underneath themselves. Turn the bowl 90 degrees and repeat for 4 folds in total. You want to repeat this process every 15 mins for a total of 4 times. You should now have a smooth-looking dough that's ready to prove. Leave this covered in the bowl to double in size. There is no specific time, but anywhere from 2-4 hours, depending on the temperature in your kitchen.
Once the dough has proven, take a non-stick baking tray - I use one 23cm x 23m/9"x 9" - and pour 2 tablespoons of extra virgin olive oil into the bottom. Put the dough into the tray, and using your hands, push it and spread it out so that it fills the tray. Liberally drizzle with more olive oil and 'dimple' the surface with your fingers until you have an even pattern of indentations across the surface of your loaf. Cover and leave to rise for 30 minutes.
Place the tray into the fridge, covered, and leave overnight or for a few hours.
When you're ready to bake, remove the tray from the fridge and leave it to rise in your kitchen for 30 minutes. Put the oven on to heat up to 220 °C
You now want to add your flavourings to your Focaccia. For a simple rosemary and sea salt, push a little sprig of rosemary into each of the indentations. Drizzle with some more extra virgin olive oil, and then sprinkle with sea salt.
Bake in the pre-heated oven for 20-22 minutes until golden and crispy. Serve as a starter to dip into balsamic and oil, or serve alongside your main dish.
Notes
See the blog post for alternative flavours for your focaccia bread
The focaccia bread will keep in a sealed bag for 2-3 days. It's nice warmed through slightly in the oven before serving.