In a medium bowl, sprinkle sugar and yeast over 1/4 cup warm water. Stir with a fork until sugar and yeast are dissolved. Let stand until foamy, about 5 minutes. Add remaining 1/2 cup warm water, along with oil, salt, and flour. Using a wooden spoon, stir until dough forms. Transfer to a lightly floured work surface; knead until smooth, about 5 minutes. Place dough in a lightly oiled bowl, turning to coat. Cover with plastic wrap; let rise in a warm place until doubled in bulk, about 1 hour.