In a large bowl, mix the flour, salt and yeast. Add the water. Using a rubber spatula, mix until the ingredients form a sticky dough ball.

Pour a tablespoon of olive oil over the top of the dough and lightly rub it all around and underneath the dough so it doesn't stick.

Cover with clingfilm and place in the refrigerator immediately for at least 12-18 hours or overnight.

After the dough has rested prick it with a fork to deflate it. 

Rub your hand with olive oil to coat and start pulling the dough from the outer sides pushing down into the middle. Rotate the bowl in quarter turns as you deflate, making it into a ball.

Spray a 9x13 or 9x15-inch low baking dish with non-stick cooking spray and pour 2 tablespoons of olive oil into the dish. (The thickness of the focaccia all depends on the size of pan using. If you use a larger dish, you will have a thinner focaccia.)

Place the dough in the pan and coat the top and bottom in the olive leaving it in the form of a ball. 

Let the dough rest and spread out on its own inside the dish for 3 to 4 hours depending on the temperature in your kitchen.

Preheat oven to 230C/450F.

Once the dough has spread out, pour another 2 tablespoons of olive oil over the dough. Rub your hands lightly in oil to coat, then using all of your fingers, press straight down to create deep dimples. If necessary, stretch gently for the dough to reach the corners of the pan. 

Sprinkle generously with flaky sea salt and top with your favourite toppings. (I used fresh rosemary, cherry tomatoes and sliced green olives. You can also use black olives instead of green or just top it with fresh rosemary.) 

Bake in oven for 30 minutes until it is golden and crisp. Remove from oven and transfer the focaccia to a cooling rack. Let it cool for 10 minutes before cutting and serving. 

Enjoy!