Place the sourdough, salt and water in a large bowl. Mix with a spatula to combine - it is not necessary to mix evenly.

Add the flour. Mix again until the flour is completely incorporated.

Let stand, covered, 30 min.

Put your hand in the bowl and pull the dough up and into the center. Turn the bowl a quarter turns and continue this pulling 8 to 10 times.

Drizzle with a splash of olive oil and spread the olive oil by hand on the surface of the dough.

Cover the bowl with a tea towel and set aside at room temperature for 4 to 18 hours (the weather will vary depending on the time of year, the strength of the sourdough and the temperature of your kitchen)

When the dough has doubled, place 2 tablespoons of olive oil in a rectangular pan.

Drizzle the dough with a tablespoon of olive oil and pour it gently into the center of the mold.

Fold the dough from top to bottom and side to side to create a coarse rectangle. Turn the dough over so the side of the seam is down.

Rub the top of the dough with oil. Leave alone for 4 to 6 hours, uncovered, until the dough is almost doubled.

Heat the oven to 230C.

With oiled hands and the ten fingers, gently press in the dough to poke holes all over the surface and stretch the dough to fit the mold.

Sprinkle generously with salt and add a few cherry tomatoes cut in 2 (flat side up) and add a few rosemary leaves.

Bake and cook for about 25 minutes or until the focaccia is golden brown.

Remove the pan from the oven and transfer the focaccia to a wire rack for cooling. Let cool for at least 20 minutes before slicing.