To prepare muffins, lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, sugar, baking powder, and salt in a large bowl; stir well with a whisk. Make a well in center of mixture.
Combine sour cream and next 6 ingredients (through egg white) in a small bowl; stir with a whisk until well combined. Add to flour mixture, stirring just until moist.
Spoon batter evenly into 10 muffin cups coated with cooking spray. Bake at 350° for 25 minutes or until muffins spring back when touched lightly in center. Remove from pans immediately. Cool completely on a wire rack.
To prepare glaze, combine powdered sugar, 1/2 teaspoon rind, and 3 tablespoons juice in a small bowl; stir with a whisk until smooth. Spread about 1 teaspoon glaze over each muffin; let stand 5 minutes or until set. Garnish with lemon rind, if desired.