In a large bowl combine the yeast, lukewarm water, flour, and salt and mix together with a wooden spoon or rubber spatula to create a wet and well-combined, shaggy dough ball. If using active dried yeast, let it dissolve in the lukewarm water for 5 minutes before mixing it with the rest of the dough ingredients. 480 g water, 2 teaspoons instant yeast, 530 g all-purpose flour , 1 ½ teaspoon fine salt
Leave it to sit for 15 minutes before applying 3-4 sets of stretch and folds spread out over an hour, one set every 15 minutes (though this timing isn't set in stone, don't worry if it's less or more). Use wet hands when doing this or the dough will stick to you.
Drizzle the bottom of a 9x13-inch pan with a generous amount of olive oil. You can line the pan with parchment paper as well if you think your pan might stick. Transfer the dough into the oiled pan. Leave it to sit and rest for 5-10 minutes, then use oiled fingers to spread and stretch the dough out into the pan. If the dough resists stretching out, give it a rest and try again in a few minutes. 4 Tablespoons extra virgin olive oil
Let the dough rise in a warm place for around 1 hour until it has doubled and it jiggles when the pan is shaken. How fast the dough rises will depend on the temperature. It's always best to watch the dough and not the clock.
Preheat the oven to 450°F / 230°C.
Slice the garlic cloves into thin slices and roughly chop the sun-dried tomatoes and fresh rosemary leaves. 3 cloves garlic, 3 Tablespoons rosemary, 10-12 sun-dried tomato halves
Drizzle a little olive oil over the surface of the dough, then use oiled fingers to create deep dimples on the top of the focaccia dough, pushing all the way down. Do this all over the entire surface.
Press the garlic slices deep into the dough. Press in the sun-dried tomato pieces and the rosemary. Sprinkle the dough with flaky salt.
Bake the focaccia for 25-30 minutes until puffed and deep golden brown and the bread pulls away from the edges of the pan. If the sun-dried tomatoes start browning too much on top, loosely cover the bread with aluminum foil.
Remove the focaccia from the oven and let it sit for 3-4 minutes. Carefully remove it from the pan, then let it cool further on a wire cooling rack before serving.