Preheat your waffle iron to a medium setting. Spray with nonstick spray. In a small bowl, combine the dairy-free milk and apple cider vinegar.
In a separate medium bowl, blend the buckwheat flour, quinoa flour, ground flaxseed, lucuma powder or sweetener if using, baking powder, and sea salt. Stir to combine.
Add the milk and vinegar mixture to the flour mixture and pour in the melted coconut oil. Whisk until a thick batter is formed (if batter is too thick, add another tablespoon of milk until desired consistency is reached).
Pour batter into waffle iron and cook according to your iron’s settings. Allow the cooked waffle to cool, about 5 minutes, before making into '“toast.”