Mash the banana really well in a large bowl, try and get it as smooth as possible.
Whisk in the oil, milk, sugar, vanilla and vinegar until well combined.
Sift in the flour, cornflour, baking powder, bicarbonate of soda, cinnamon, nutmeg and salt. Whisk with a balloon whisk until just combined, do not over-beat the batter.
Set the batter aside to rest while you heat up your waffle iron.
Spray the waffle iron with cooking spray or brush with oil and ladle in some batter (the amount you need will vary depending on your waffle machine). Cook until golden brown and steam stops coming out of the waffle maker. The time they take to cook will vary depending on your machine so just keep an eye on them.
Repeat with the rest of the batter, oiling the waffle iron in between each batch. To keep the cooked waffles crisp, lay them in a single layer on a baking sheet in a low oven.