In a large bowl, stir the yeast and sugar into a cup of warm water; set aside for 5 minutes, until it’s foamy. (If it doesn’t get foamy, either your water was too hot and killed the yeast or it was inactive to begin with – toss it and buy fresh yeast or try again!)
Add 2 1/2 cups of the flour, salt and oil and stir until the dough comes together. On a lightly floured surface, knead the dough for about 8 minutes, until it’s smooth and elastic, adding a little more flour if the dough is too sticky.
Place the dough in an oiled bowl and turn to coat all over. Cover with a tea towel or plastic wrap and set aside in a warm place for half an hour to an hour, until doubled in bulk. If you want you can let it rise more slowly in the refrigerator for up to 8 hours.