In a small bowl, mix warm milk with sugar, then sprinkle yeast over it. Let it sit for 5-10 minutes until the yeast is activated and bubbly.
In a large bowl, combine all-purpose flour, cornstarch, and salt. Make a well in the center.
Add the yeast mixture and vegetable oil to the well. Gradually mix the wet ingredients with the dry ingredients until a dough forms.
Knead the dough on a floured surface for about 10 minutes until it becomes smooth and elastic. If the dough is too sticky, add a bit more flour as needed.
Place the dough in a lightly oiled bowl, cover with a damp cloth, and let it rise in a warm place for about 1-1.5 hours, or until it doubles in size.