Make the sponge: In a large bowl, proof 1 teaspoon of the yeast in 1/4 cup water until bubbly - about 10 minutes. Add 3/4 cup of the flour, stir to combine and let rise, covered with plastic, for 45 minutes, or until mixture if bubbly.
Meanwhile, in another bowl proof remaining yeast in remaining water until bubbly - about 10 minutes.
Add second yeast mixture and olive oil to the sponge, stir in 1 cup of the flour and add remaining flour in two batches, stirring well after each addition, until mixture forms a dough.
Transfer the dough to an oiled bowl, turn it to coat with the oil and let rise, covered with plastic, until doubles - about 1 hour.
Yield: 1 focaccia loaf