All ingredients ready? Let's begin!
In a large mixing bowl, place the warm water. Make sure it isn’t too hot. Add the yeast and stir gently. Sprinkle the sugar over the yeasted water. Set this aside until the yeast bubbles for at least 5 minutes.
Add the sea salt and 1/2 cup of olive oil to the water and stir gently again.
Add the flour to the liquid and stir with a wooden spoon to combine well until the dough starts to pull away from the sides of the bowl and it comes together into a sticky ball.
Lightly flour a flat work surface. Turn the ball of dough out onto the floured surface. Add some more flour on top of the ball of dough. Using the heels of your hands, knead the dough for 5 to 10 minutes until it is elastic and no longer sticky, adding a little more flour as needed.
Add 2 tablespoons of oil to the bowl and coat the sides. Place the ball of dough in the bowl and roll it over to coat all sides with the oil.
Cover the bowl with plastic wrap. Place the bowl in a warm space or inside a turned-off oven with the light left on. Allow the dough to rise until doubled in size, at least 60 minutes
Coat a rimmed baking sheet with 3 tablespoons of olive oil. Place the dough in the pan and spread it out with your hands. Once the pan is full, use your fingers to punch holes in the dough all over. Place the pan back in the oven with the light on and allow the dough to rise again for another 60 minutes.
Remove the pan from the oven carefully so the dough doesn’t deflate.
Preheat the oven to 425°F.
Drizzle or brush the remaining 3 tablespoons of oil over the dough. Sprinkle coarse salt over the top of the dough. Place the focaccia in the preheated oven and bake until golden brown, approximately 25 to 30 minutes.
Remove the focaccia from the oven and allow it to cool before slicing it so the steam doesn’t escape.
Slice the focaccia with a serrated bread knife and serve as is or make it into sandwiches with greens and prosciutto.