In a bowl, stir together yeast, sugar and water and proof yeast for 10-15 minutes, or until foamy.
Stir in 4 cup of flour, 1 Tbsp of the olive oil and the salt, adding as much of the remaining flour as necessary to form a soft and slightly sticky dough.
Transfer to a lightly-oiled bowl, turn to coat, and let rise, covered, in a warm place for 1 hour, or until double in size. Knead dough down and press with lightly-oiled hands into a well-oiled 15 ½ x 10 ½ inch jelly-roll pan and let it rise, covered loosely, for 30 minutes.
Preheat oven to 375 degrees F. Set rack in center of oven.
Dimple dough with your fingers in places, drizzle 2 Tbsp olive oil over and spread over dough; sprinkle with rosemary, garlic and sea salt.
Bake for 35-40 minutes or until pale golden. Let cool for 10 minutes before cutting. Serve warm or at room temperature.