Bring a pot of water to a boil over medium heat. Then peel and cut a Yukon golden potato into cubes. Add it to the boiling water and cook until tender. Remove the potato and mash it into a small bowl. Set aside to cool.

Meanwhile, add 1 cup of lukewarm water to the countertop mixing bowl. Followed by the sugar and sprinkle the dry active yeast on top. Let the ingredients stand for 5 - 10 minutes until the yeast is foamy. Do not mix the ingredients together - the yeast will begin its process immediately.

Once the yeast is foamy (should almost cover the entire surface of the water), add the remaining 1 cup of lukewarm water, olive oil, and salt. Using the dough hook attachment, mix the ingredients together until combined. Add the all-purpose flour, semolina flour, and mashed potato to the mixing bowl. Start on the lowest speed, and mix all the ingredients together.

When the ingredients are combined well, increase the speed to medium to begin the kneading process. The dough should be kneaded for 10 - 20 minutes until it is smooth and elastic. The dough will be ready when it forms into a ball. You can also take a rubber spatula and scrape the dough against the bowl. If the dough keeps its shape, it is ready. Also note, this is a wet dough, so it will be sticky.

Lightly grease a 9 x 13 in. baking pan and place the focaccia dough in it. Carefully spread the dough evenly into the pan. Then cover the pan with plastic wrap and let the dough rest in a warm place for 1 - 1 and a half hours. The dough is ready when it has doubled in size and risen at least 3/4 to the pan level.

While the dough is resting, begin roasting the cherry tomatoes. Preheat the oven to 400°F.

Slice the cherry tomatoes lengthwise and set aside. In a small bowl, combine the olive oil, minced garlic, minced rosemary, salt, and pepper together. Then toss the cherry tomatoes into the bowl until they are well coated.

Place the cherry tomatoes cut-side up on a baking sheet lined with parchment paper. Bake the cherry tomatoes for 25 minutes or until they are blistered. Remove from the oven and let them cool. Lower the oven temperature to 375°F.

Once the focaccia dough has doubled in size, carefully remove the plastic wrap. Pour some olive oil in a small shallow bowl and dip your fingers into it. Then using your fingers, make small indentions into the focaccia dough. Sprinkle coarse sea salt and minced garlic evenly on the dough. Followed by firmly pressing the roasted cherry tomatoes into the dough.

Bake the focaccia at 375°F for 35 - 40 minutes, rotating the pan halfway through. The focaccia is baked to perfection when the edges and the top are beautifully golden brown.