In a large shallow bowl, whisk flour, sugar, baking powder and salt.
In a separate bowl, combine milk, vegetable oil, eggs and vanilla.
Make a well in the center of the dry ingredients. Pour in the wet ingredients. Stir with a wooden spoon or whisk until batter is mostly combined, leaving larger lumps. Be sure there are no large pockets of flour at the bottom of the bowl.
Rest batter 5 minutes. Preheat waffle iron.
Gently stir batter with a whisk to break up remaining large lumps. Small lumps are ok.
Cook according to waffle iron directions.
Serve waffles immediately if possible.
To keep waffles warm: Heat oven to 200°F. Place waffles in single layer directly on the rack until ready to serve.