Pre-heat the oven to 400º F, and either grease a baking sheet or add parchment paper to it.
In a glass measuring cup or bowl, beat together the egg, almond milk, and apple cider vinegar. Set aside for a few minutes, until the mixture begins to slightly curdle, giving it a buttermilk-like taste and texture.
In a separate large mixing bowl, whisk together the flour, xanthan gum, baking powder, baking soda, salt, and sugar.
Slice the cold vegan butter into the dry ingredients. Then using a pastry blender, cut the butter into the dry ingredients 'til it resembles fine crumbles.
Mix the almond milk and egg mixture into the dry ingredients.
Drop the dough, by the spoonful, onto the prepared baking sheet.
Bake at 400º F for about 30 minutes, or 'til the biscuits turn a light golden color on top.
Serve warm with vegan butter, strawberry jam, apple butter, etc.