Chill coconut oil in the fridge for 30 minutes.
Stir the dry ingredients together: flour, salt, and baking soda. If you do not have the gluten-free flour already made you have to premix it. (see notes)
Cream cold coconut oil, sugar, egg, and vanilla until light.
Slowly add in the dry ingredients.
Form the dough into a 2 inch diameter roll. Wrap in plastic wrap and shape up so it is even.
Place in the fridge for at least three hours till overnight...you can also freeze at this point for months until you are ready to use. Or save in the fridge for up to a week until you are ready to use.
Start the blueberry sauce:
Put the frozen blueberries in a saucepan with a few tablespoons of water and the sugar.
Cook until soft and dissolved over medium low heat, about 20 minutes. Keep simmering over low heat.
Temper your tapioca flour by dissolving in approximately a tablespoon of water. Add a large wooden spoonful of the hot blueberry mixture to your dissolved tapioca flour. Rapidly whisk in the tapioca mixture to the rest of the blueberries. After 2 minutes, turn off the heat.