Mix flour, yeast and salt. Combine water and olive oil, stir into flour mixture. Flour your hands, and mix and knead the dough until smooth, adding more water if necessary. Shape into a ball, place in a plastic bag and refrigerate at least one hour or until ready to use, up to 4 hours. When ready to assemble pizzas, roll out on a floured surface into two 12 inch pizza bases and use in a pizza recipe.