In a medium-sized bowl, whisk the plant-based milk, vinegar, oil and vanilla. In a large bowl, sift the flour, sugar, cornstarch, baking powder, and salt together. Add the wet ingredients to the flour mixture, and whisk just until blended. Don't over-mix, some lumps are fine. Let the batter rest for 5 minutes.
In the meantime, melt the vegan butter in a small bowl. In a separate wide bowl, mix the 1/2 cup sugar and cinnamon.
Cook the waffles according to the manufacturer's instruction, spraying the waffle iron with oil before each waffle.
Brush each waffle all over with the melted vegan butter, and lightly dust with the cinnamon sugar, shaking out the excess.