In a large bowl combine oat flour, buckwheat flour, rice flour, baking powder, baking soda, and sugar.
In the other bowl combine soy milk, lemon juice, vanilla extract, and apple sauce.
Pour the wet ingredients into dry and combine. Next, add melted vegan butter. The batter should be creamy, smooth, and fluffy.
The very last step is to add blueberries. Carefully combine, and spoon the batter into a muffin pan lined with parchment paper or silicone muffin cups.
Bake them at 400F (200°C) for about 25 minutes. Serve dusted with powdered sugar. Enjoy!