Begin by measuring the flour and 1 teaspoon of the salt into a large mixing bowl, then sprinkle in the yeast and mix that in and make a well in the centre.
Next pour in the hand-hot water along with 1 tablespoon of the olive oil and mix everything with a spatula to a dough that leaves the sides of the bowl clean (if necessary you can add a few more drops of water).
Now place the bowl with the dough in roomy polythene bag, close it with a clip and leave at room temperature until it has doubled in size (about 1½ hours or more depending on the heat in the kitchen).
After that turn the dough out on to the work surface and punch the air out by kneading it briefly. Brush 1 tablespoon of olive oil over the liner in the tin and press the dough into the tin using your fist, so its evenly spread out into the corners, then use your hands to flatten it out all over and place the tin into a large oiled polythene bag.
Close it with a clip and leave it at room temperature for 1 hour until it has risen to the top of the tin.
Next, remove the bag and make indentations all over the top of the dough with your finger, so that you go almost all the way down to the base of the tin but without breaking through it. Then whisk together the 2 remaining tablespoons of olive oil with 2 tablespoons of water and the remaining teaspoon of fine salt until it emulsifies.
Now drizzle this all over the surface of the bread so it flows into all the indentations. Then break off small sprigs of rosemary and push one into each of the indentations, finally scatter a few more rosemary leaves all over.
Now pop it back into the bag, again closed with a clip, and leave to puff up again for 15 minutes.
Meanwhile,pre-heat the oven to gas mark 220C, gas mark 7.
When the 15 minutes are up sprinkle the surface with the salt flakes then bake the bread in the oven near the centre for 20 – 25 minutes until crisp and golden brown. Lift the bread from the tin by holding the liner at the sides onto a wire rack.
Then use a palette knife to help you slide the foccacia off the liner onto the rack to cool a little.
Serve warm, with a little dish of Italian extra virgin olive oil to dip into.