In the 4 qt bowl, pour warm water then add sugar and yeast and stir for a couple of time then let it proof for 5 minutes.
Mix flour, yeast, sugar and salt then pour in warm water.
Mix ingredients with a spatula or a wooden spoon until flour disappears. You will get a sticky shaggy dough.
Pour 1 tablespoon oil over and rub with your hands all over the dough surface then cover and refrigerate overnight and up to 5 days.
Wet your fingers with a little oil and deflate the dough by pulling it from the sides of the bowl to the center to make a ball.
Butter a 13x9 glass baking dish making sure the bottom and sides are well coated and pour 2 tablespoons in the center of your dish.
Grab your dough ball and place it in the center of the baking dish. Cover and let it rise and get bigger until it fills the pan. This will probably take about 3-4 hours depending on the temperature of your kitchen.
Preheat oven to 475F.
Uncover the dough, wet your fingers with some oil and start dimpling the dough all over.
Sprinkle sea salt flakes generously on top.
Bake in the center of your oven for 20-25 minutes until lightly browned.
Take out of oven and brush with the remaining tablespoon of olive oil.
Take it out of the baking sheet and let it cool for like 10 minutes before slicing and serving.