In a large bowl or stand mixer, combine the warm water, sugar, yeast, salt, and ¾ of the all-purpose flour. Mix until combined. Knead (by hand or with a stand mixer with a dough hook) until the dough is smooth and elastic (about 10 minutes), adding the remaining flour as needed to keep the dough from sticking.
Brushing dough ball with olive oil also place in bowl covered with damp kitchen towel. Let rise until doubled in volume (about 1 hour).
Place parchment paper on a large baking sheet. Drizzle parchment paper with oil.
Once the dough has doubled in volume, degas it. Roll out the dough and stretch it to fit the baking sheet. Cover lightly with plastic wrap and leave until doubled in size (about 40 minutes).
While the dough is rising, preheat the oven to 450°F (230°C) and prepare the topping.
Time dough has risen, add your choice of toppings. Use your fingers to dig in the dough well, and press the filling onto the bread. Drizzle with olive oil and season with fleur de sel.
Bake the focaccia until golden brown, about 25 to 30 minutes.

Enjoy !