Activate the Yeast: In a small bowl, mix warm water, sugar, and yeast. Let it sit for 5-10 minutes until it becomes frothy.
Make the Dough: In a large mixing bowl, combine flour and salt. Add the yeast mixture and olive oil, stirring until a shaggy dough forms.
Knead and Rise: Transfer the dough to a floured surface and knead for about 5 minutes until smooth. Place in a greased bowl, cover with a kitchen towel, and let it rise for 1-2 hours, or until doubled in size.
Shape and Proof: Grease a 9x13-inch baking pan with olive oil. Spread the dough evenly, pressing it gently with your fingertips to create dimples. Cover and let it proof for another 30 minutes.
Bake: Preheat your oven to 400°F (200°C). Drizzle the dough with olive oil, sprinkle with rosemary and flaky sea salt, and bake for 20-25 minutes or until golden brown.
Cool and Serve: Let the focaccia cool slightly before slicing and serving. Enjoy warm or at room temperature!
