Pour the flour into a bowl and make a depression in the middle. Crumble the yeast into it, mix with 100 ml lukewarm water and a little flour from the rim. Dust with a little flour, cover and leave to rise in a warm place for about 15 minutes
Add salt, approx. 150 ml lukewarm water and 4 tablespoons of olive oil and knead to a smooth dough. Cover the dough and let it rise in a warm place for about 1 hour
Wash the rosemary, shake dry and pluck roughly into pieces. Grease a baking tray (34 x 41 cm) and dust with flour. Knead the dough again slightly and roll it out on the baking tray to a large flat cake (approx. 28 x 38 cm). With floured fingers press evenly into the dough and drizzle 4-6 tbsp. olive oil into it. Sprinkle with sea salt and rosemary. Cover and leave to rise again for approx. 45 minutes
Bake the focaccia in a preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: see manufacturer) for 15-20 minutes
waiting time approx. 2 hours