Add flour and yeast to a large mixing bowl. Add salt, honey, 4 tsp. crude olive oil and water. Mix with a spoon until dough is wet and sticky.
Cover and let the dough rest at room temperature for 12 to 14 hours.
Transfer the dough to an oiled baking sheet. Stretch the dough to completely cover the surface of the baking sheet, cover and let rest for one hour. With lightly oiled fingers, punch holes in the dough. Add candied onions, rosemary and remaining fleur de sel.
Bake in a preheated 425°F oven for 30 minutes or until dough is well coloured and crisp.
Place cooked focaccia on a wire rack and let cool for about 30 minutes before serving.