Preheat waffle iron.
In a medium bowl, whisk together the milk, vegetable oil, egg, and vanilla until well combined.
In a separate bowl whisk together the mochiko, baking powder, salt, and sugar.
Now combine the wet and dry mixtures in a bowl until they are completely combined and smooth. It should be the consistency of pancake batter, a little thick but not too thick, add more milk if needed.
Spray preheated waffle iron with non-stick cooking spray. Pour mix onto the hot waffle iron. Cook until golden brown. Serve hot.