Preheat waffle iron. For irons with temperature controls, set it on medium. You can also preheat your oven to 225°F if you want to keep your finished waffles warm as you make them.
In a small bowl, whisk together the flour, baking soda, baking powder and sea salt.
In a large bowl, whisk together the yogurt (or buttermilk) and eggs. Add the potatoes, chives, cheese to the bowl and mix together until combined. Grease the waffle iron with butter, then pour remaining butter into potato mixture. Fold the flour mixture into the potato mixture until combined.
Scoop 1/2 a cup to 2/3 cup of potatoes (depending on its size) into your waffle iron. Use a spatula to spread evenly. They won't spread like regular batter, so it's important to spread evenly. Close iron and cook until golden brown and crispy. If keeping them warm, place into oven or serve right away. Repeat the process with the rest of the batter.