Put flour in a large bowl and create a well in the center. Dissolve yeast and sugar in 1/4 liter (approximately 1 cup) of lukewarm water and pour into well. Cover and let rise for 30 minutes.
Stir 3 tablespoons olive oil and salt into dough and knead for about 10 minutes. Add more 1/8 liter (approximately .5 cup) of water if needed. Cover and let rise again until volume has doubled, about 1 hour.
Preheat the oven to 220°C (approximately 430°F). Split dough in half and roll out onto a floured surface. Cover and let rise for another half hour.
Brush with remaining oil. Rinse, core and slice apples. Spread apples onto dough. Divide rosemary into small bunches and sprinkle with a little coarse salt onto dough. Bake on the middle rack for about 20 minutes. Remove, slice and serve.