Any wine that is fully fermented (meaning the yeast eats all the sugar) will be sugar free (0-0.15g per glass). Wine is made by adding yeast to grape juice. Then, the yeast eats the sugar, producing alcohol and carbon dioxide as byproducts.
Modern, industrial winemakers use sulfur dioxide, commonly known as sulfites, to kill the yeast early, which leaves residual sugar in the wine. And, some even add sugar back into the wine. This achieves a sweeter palate to appeal to the American market.
By contrast, natural winemakers utilize a full fermentation when creating their wines. This is when a winemaker lets the native yeasts consume as much as sugar as possible until the yeast naturally dies. In this full fermentation, the yeast eats the sugar and dies.
We lab test every bottle for sugar so none of our bottles measure beyond 1g / L of sugar. Since wine doesn't have nutrient labels, lab-testing gives us the certainty to avoid consuming sugar.