-Preheat oven to 480° F
-Mix the flour, yeast and salt in a large mixing bowl
-Pour in the water and olive oil
-Stir everything together
-When the mixture has mostly stuck together, turn the mixture out on to a work surface
-Knead the mixture by holding one end of the dough in one hand and stretching it out with the other hand, for 10 minutes
-When the dough is shiny and smooth, put it in a large mixing bowl, coat it in a thin layer of olive oil and cover the bowl with a towel
-Leave in a warm place until it has doubled in size
-Flatten and shape the focaccia in an oiled baking tin with your hands, making sure you stretch it into the corners
-Push the cherry tomato halves into the focaccia
-Coat with olive oil and sprinkle with rosemary and salt
-Cover with a towel and leave in the tin for a 15 minutes
-Bake for 10 min then turn the oven down to 390° F and bake for another 10-15 minutes until the top is golden brown