Preheat the oven to 425°F. Line a 12-cup muffin tin with papers and grease the inside of the papers.
Combine the dry ingredients in a mixing bowl.
In a small bowl, whisk together egg replacer and water. Let sit 1-2 minutes.
In a second bowl, whisk together the starter, milk, egg replacer, melted coconut oil, maple and vanilla. Blend the wet ingredients with the dry, taking about 20 seconds. Gently stir in the blueberries just until blended.
Fill the cups of the prepared pan two-thirds full; sprinkle the tops of the muffins with sugar.
Bake the muffins for 16 to 20 minutes, until a toothpick inserted in the center comes out clean. Remove the pan from the oven and allow the muffins to cool for 5 minutes before removing them from the pan. *Don't let them cool in the pan, or they'll steam and the outside will become tough.