Makes one slab, in a 9x13 inch deep sided baking tray
The dough can be made by hand or in an electric mixer. I prefer to bake it in a deep-sided tray so the dough and oil are contained. I find the edges crisp up better during the bake and it won’t dry out after baking.
To make the dough by hand, combine the flour, 450g of water, yeast and salt in a medium sized mixing bowl. Mix with your hands until you have a cohesive mass, and then scrape down the bowl and your hands. Stretch and fold the dough for around 5 minutes to build up strength. Once it is getting stronger and if it is not too sticky, mix the remaining 30g of water followed by the olive or lemon oil. This should take another 5 to 6 minutes. The dough will be quite wet and sticky but don’t worry, as the pan will hold it together.
To make the dough in a mixer, combine the flour, 410g of water, yeast and salt in the bowl. Mix with the dough hook for 5 minutes on a medium speed until it all comes together. Scrape down the sides of the bowl, and then add the remaining 70g of water and the oil. Continue to mix on a medium speed for another 5 minutes until it is smooth and quite elastic. You should be able to stretch the dough with your hands. The dough will be stronger in the mixer.
Once the dough is mixed, cover it in the bowl with a damp tea towel and rest for 30 minutes.
Give the dough a fold every 30 minutes for the first 2 hours. To fold, wet your hands and grab a piece of dough on the side of the bowl. Pull and stretch it up over the middle to the other side of the bowl. Repeat this 6–8 times, moving around the edge of the bowl. Cover and rest the dough between folds. It should become very strong and stretchy over time.
After the third set of folds, cover and rest the dough for 30 minutes more, ideally at around 23°C–24°C. If it is too cold you can place it into your (cold) oven with a pan of hot water at the bottom to create warmth and humidity.
Take a deep-sided baking tray and line it with baking paper or a generous amount of olive oil. Wet your hands and place the dough into the middle of the tray and use your fingertips to gently massage and stretch the dough into the corners, so it is fairly even in depth. Cover once again and leave it in a warm place to prove. The time this will take will on the temperature; if it’s cooler let it prove longer, if it’s warm you will be able to bake sooner. As a guide it should take one to two hours at a temperature of between 22°C–24°C. It’s ready when the dough has risen by half and is nice and bubbly and wobbly as you shake the tray. If you poke it with your wet finger should be soft; if it springs back quickly it is under proved so give it more time in a warm place.
Preheat your oven to 230°C about 20 minutes before you bake. Place one shelf at the top of the oven for the focaccia and one below with a small shallow tray on it. (Later you will pour a small amount of hot water into this tray to create steam, which helps the dough rise during the initial part of the bake).
Drizzle two thirds of a tablespoon of olive oil over the top of the focaccia. Oil your fingertips and gently push them into the dough until your can feel the bottom of the pan, leaving space between each press. Scatter with the chopped rosemary and coarse salt, and press the olives gently into the dough so that they are still exposed on top.
Place the focaccia onto the top shelf and pour 100ml of boiling water into the tray on the bottom. Bake for 22–25 minutes until golden on top. Turn the tray and remove the steam tray halfway through the bake.
Once baked, leave to cool in the pan for a couple of minutes before transferring to a wire cooling rack.
This focaccia is wonderful to eat still hot from the oven, and will keep well for a few days if manage to resist eating it all on day one.