Position a rack in the upper third of oven and preheat to 375°F. Line a 12-cup standard cupcake tin with paper liners.
Whisk, measure and sift together the flour, sugar, coconut sugar, baking soda, baking powder and salt into a medium bowl. *Note: If the gluten-free baking mix does not contain xanthan or guar gum, add 1 tsp to the dry ingredients.
Place the plant milk, oil, vanilla and vinegar in a medium bowl , whisking to blend completely. Pour the wet mixture into the dry mixture and whisk until the batter is smooth. Note that this batter is a bit thicker than a gluten-based batter.
Spoon an equal portion of the batter into each of the lined cups, filling about 2/3 full. (Repeat with any extra batter.)
Transfer to the preheated oven and bake for 18 to 20 minutes or until the tops of the cupcakes are set and a tester or wooden toothpick inserted into the center comes out clean or holds just a few moist crumbs.
Remove from the oven and set the tin on a wire cooling rack for 5 minutes. Use a small offset spatula to carefully lift the cupcakes out of the tin onto the cooling rack. Take care as the cupcakes are tender while they are hot. Allow to cool to room temperature.
When cool, transfer to the refrigerator to chill before frosting. If making ahead or if you have leftover cupcakes, store, covered and refrigerated, for up to 2 days.
The cupcakes may also be stored, airtight and frozen, for up to 2 months.. If the latter, remove from the freezer and defrost, uncovered, when ready to serve.
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