Put the yeast and sugar in the container.
Slowly pour in the lukewarm water, and whisk energetically to mix the sugar and yeast into the water. Let the mixture sit for 10 minutes to allow the yeast to activate.
When the yeast mixture is frothy, add the flour and then pour the salt over the top of the flour. Mix everything thoroughly with your hands until the dough is smooth and elastic.
Pull a section of the dough away from the edge of the container to make a small well and pour in a quarter of the extra-virgin olive oil. Repeat this step three more times until you have used all the oil.
Fold the oil into the dough using a folding technique. Seal with a tight-fitting lid and put it in the fridge to rest for 18–24 hours.
Butter a 30 cm × 25 cm stainless steel tin very well. Pour in 60ml (¼ cup) of oil.
Take the dough out of the fridge and fold it into the centre multiple times. Put it into the tin seam side down.
Leave the dough to rise for 3-4 hours or until it has doubled in size.
Preheat the oven to 220C fan-forced (240C conventional).
Drizzle oil over the focaccia, dimple the surface, sprinkle with flaky salt, and drizzle with more oil.
Bake for 30 minutes, then increase the heat to 245C and bake for a further 10 minutes.
Let it cool in the tin for 5 minutes, then transfer to a cooling rack.
