In a large bowl or mixer fitted with dough hook, combine the water, yeast and sugar, cover and set aside for 10-15 minutes until foamy. 

Add 2 ½ of the cups of flour, 2 teaspoons of the salt, 1/4 cup of the olive oil to the yeast mixture. Mix well. Continue kneading in the mixer bowl or by hand, adding the remaining ¼ cup of flour as needed to make a smooth, soft dough.

Drizzle the dough with ¼ cup of the olive oil, turn dough to coat the inside of the bowl. Cover with plastic wrap and put in a warm place for one hour until doubled in size.

Remove dough to a heavy baking pan (a dark metal pan works best), include any oil from the bowl. Press the dough out and stretch to cover the pan. Using your fingers, dimple the entire surface, making holes through the dough. This creates the characteristic focaccia surface that can to hold on to toppings. Cover with plastic wrap and let rest at room temperature for 30 minutes to an hour.

Place rack in the middle of the oven. Preheat oven to 425°F. Dimple dough again and sprinkle with remaining tablespoon of coarse salt. If desired, add 1 to 3 of the optional toppings. Drizzle surface with the remaining tablespoon of olive oil.

Bake in the preheated oven for 20 to 30 minutes, until deep golden brown. Remove the focaccia from the oven and let it cool before cutting and serving.