Preheat oven to 400°F. Coat standard 12-cup muffin tin (2” diameter base, 1-1/4” deep) with cooking spray or use paper muffin liners, set aside.
Stir together flours, gelatin powder, xanthan gum, baking powder, sugar (if using honey, add with liquid ingredients) and salt in large bowl. Make well in center.
In a small bowl, whisk together milk, oil, eggs, vanilla extract, and lemon peel. Pour into well of flour mixture. Stir just until ingredients are moistened. Gently fold in blueberries. Batter will be very soft. Spoon batter into muffin tins.
Bake for approximately 25 minutes, or until tops of muffins are lightly browned.
Remove from oven. Combine powdered sugar and lemon juice to form glaze. Brush or drizzle over warm muffins.