Prize Winning Blueberry Muffins

½ c sugar
¼ c butter, softened
1 c sour cream
2 Tbsp lemon juice
1 tsp grated lemon zest
1 egg
1-1/2 c all-purpose flour
1 tsp baking soda
1 c fresh or frozen (unthawed) blueberries
1 Tbsp sugar
½ tsp grated lemon zest

Heat oven to 375°F. Grease muffin pan cups or place paper baking cups into muffin pan cups; set aside. Combine 1/2 cup sugar and butter in large bowl. Beat at medium speed, scraping bowl often, until creamy. Add sour cream, lemon juice, 1 teaspoon lemon zest and egg. Continue beating, scraping bowl often, until well mixed. Combine flour and baking soda in medium bowl. Stir flour mixture into sour cream mixture by hand just until moistened. Gently stir in blueberries. Spoon into prepared muffin pan cups. Combine 1 tablespoon sugar and 1/2 teaspoon lemon zest in small bowl. Sprinkle about 1/4 teaspoon mixture on top of each muffin. Bake for 20 to 25 minutes or until lightly browned. Cool 5 minutes; remove from pan.