2 cups (470g) water (but see the instructions for more info)
2 tsp (11g) salt
1 tbsp extra virgin olive oil, plus lots more for greasing the tray and drizzling
7g dried yeast (any kind of dried yeast—active or instant— will work)
4 cups (560g) bread flour or Italian 00 flour, with 12% protein content (please see the discussion about flours above)
Make the dough
In a large bowl combine the water, salt, olive oil and yeast. Give these a whisk.
Add the bread flour and mix using a large spoon or spatula until well combined and hydrated.
Scrape down the sides and cover the bowl for 30 minutes.
We are going to perform four rounds of "stretches and folds". Take one side of the dough, stretch and fold bringing the dough to the opposite side of the bowl. Rotate the bowl one quarter and repeat another 3 times.
Cover the bowl and leave for 30 minutes.
Repeat the stretch and fold process another 3 times, leaving 30 minutes in between each round.
After your last series of stretch and folds, cover the dough with plastic wrap and place in the fridge over night.
If you want to, you should be able to cold-ferment this dough for up to 48 hours in the fridge, for even better flavor development. If you leave it longer than that, you risk it over proofing, which means the dough won’t rise in the oven and support big bubbles as it bakes.
Or, if you want a quicker result, you can skip the cold fermentation in the fridge completely. Instead, you can simply allow the dough to sit one last time at room temperature for 30 to 40 minutes.
Into a 9x13 inch tray (at least 2 inches deep) add 3 to 4 tbsp of olive oil. Be generous with the oil, focaccia craves it. Grease the tray well. (If your tray is not non stick, line the bottom with parchment paper before adding the oil.)
Carefully perform one last series of stretches and folds and then gently place the dough into your tray. Drizzle with more olive oil.
Cover well and allow to proof one last time for at least 1 hour. Please note: if you cold-fermented the dough in the fridge overnight, the dough will need to rise in the tray for around 2 hours at room temperature because it will still be cold from the fridge.
After the final proof, drizzle the dough with more olive oil (yes, really!). Then, cover your hands with oil, and gently make dimples in the dough. Jiggle the dough to spread the it out in the pan.
Preheat the oven to 400°F (200°C) with the fan on (if your oven has a convection fan) and bake the focaccia for about 20 to 25 minutes (it's done when the top is golden and crispy).
Remove from the oven and wait for at least 10 to 15 minutes before slicing into it. (Focaccia can be served warm or cold - it’s great when it’s still warm because the outside will still be crispy).