Preheat oven to 400 degrees F. Spray muffin pan with nonstick cooking spray or line with paper muffin liners.
In a small bowl, combine sugar and lime zest. Mix with clean fingertips until sugar is moistened and fragrant. Set aside.
In a medium bowl, stir together flour, salt and baking soda. Set aside.
In large bowl, beat eggs and sugar until thoroughly incorporated. Continue beating while slowly pouring in the oil. Add in vanilla.
Stir dry ingredients into egg mixture alternately with sour cream. Gently fold in blueberries. Scoop batter into prepared muffin cups and if desired, top with a sprinkling of coarse sugar.