Preheat waffle iron.
In a medium bowl, combine kefir/buttermilk, oat milk, melted butter, and eggs.
In a large bowl, combine the flour, sugar, salt, baking powder, and baking soda. Pour in the liquid ingredients and stir to combine.
Spray waffle maker with nonstick spray (or use butter) and ladle out the batter per waffle maker instructions. (If not sure, start with 1/4 or 1/3 cup of batter.) Cook for about 2-3 minutes, or until waffle maker indicates waffle is done. Waffle should be golden brown.
Use a fork to remove the waffle. Serve immediately or transfer to a wire cookie rack so that they don't get soggy on the bottom. Enjoy with your favorite toppings!