In a large mixing bowl, combine the egg, melted butter, buttermilk, sugar and salt. Give it a whisk.
Sift in the baking powder, baking soda, all-purpose flour and potato starch.
Gently fold the batter with a spatula, until just combined. Be careful not to overmix.
Heat up a waffle iron/maker over medium-high heat. Carefully grease the waffle maker with a little melted butter/oil.
Scoop about ¼ C of batter into each quarter of the waffle maker (if using a round waffle maker).
Close the waffle iron/maker and let it cook for 4-5 minutes, until golden brown.
Remove the waffle and place onto a wire rack to cool.
Repeat with the remaining waffle batter.
Cut each waffle into 4 quarters.