Place the potato in a pot with boiling water and cook for 20 mins. Let it cool.
In a large bowl mash the boiled potato with a fork. You may add a small amount of water just to puree it well so there are no pieces left.
Mix it well with the flour, yeast, sugar, salt, rosemary, and water until a well-combined dough is formed.
Cover and leave to a warm place for about 40 mins to rise.
When the dough has reached twice its volume, knead it for about 5 mins, adding just a little more flour to prevent sticking. The dough should be smooth and elastic.
Line a baking tray with parchment paper and spread the dough in it, pushing it to the corners of the tray.
Preheat the oven to 400°F (200°C).
Use your fingers to form dimples on the surface of the dough. Cut the cherry tomatoes in halves and start inserting them deep into the dough. Sprinkle with some fresh finely chopped rosemary and salt. Set it aside for about 20 mins to rise.
Bake the foccacia bread for 20 mins or until slightly brown.
Cool before eating. Enjoy!