Combine flour, baking powder, baking soda, and salt in a medium bowl and set aside.
In a large mixing bowl, beat egg, yolk, and sugar until thickened, about 2 minutes.
Mix in oil and vanilla until well blended.
Mix in sour cream until no white streaks remain.
Add flour mixture and blend until batter is smooth.
Stir in toasted coconut and lime zest.
Pour into 12 muffin tins lined with cupcake liners.
Bake at 350 degrees for 23 minutes.