Ingredients

• 1 1/4 cups milk
• 1 tablespoon vinegar
• 3/4 cup white sugar
• 1/2 cup butter, softened
• 2 eggs
• 1 egg yolk
• 1 tablespoon freshly grated lemon zest (optional)
• 1 1/2 cups rice flour
• 1 cup cornmeal
• 4 teaspoons baking powder
• 1/2 teaspoon salt
• 1 cup blueberries
• 1 tablespoon raw sugar, or to taste (optional)

Instructions

1. Preheat oven to 400 degrees F (200 degrees C). Line 12 muffin cups with paper liners.
2. Stir milk and vinegar together in a small bowl; set aside to sour for 3 to 5 minutes.
3. Beat white sugar and butter together in a bowl using an electric mixer until creamy and smooth. Add eggs, egg yolk, soured milk, and lemon zest; beat until smooth, scraping down sides of bowl as needed.
4. Mix rice flour, cornmeal, baking powder, and salt in a bowl; slowly stir flour mixture into creamed butter mixture until just mixed. Gently fold in blueberries. Pour batter into the prepared muffin cups, filling each about 3/4 full. Sprinkle each muffin with raw sugar.
5. Bake in the preheated oven until a toothpick inserted in the center of a muffin comes out clean, 18 to 20 minutes.