In a medium bowl, whisk together the sorghum rice and buckwheat flours with the milk and the lemon juice. Cover and allow to sit overnight.
The next morning, uncover the flour mixture and whisk in the melted oil, eggs and rapadura. Set aside.
In a separate, small bowl, whisk together the starch, baking powder and sea salt. Whisk into the wet ingredients.
Cook according to the instructions of your waffle maker. For my waffle maker, I have it set to a medium-high time setting in order to get the waffles done all the way through.
Recipe by Grain Mill Wagon at https://www.grainmillwagon.com/soaked-gluten-free-waffles/