- For the batter, whisk the sour cream, sugar, egg, vanilla and lime zest in a bowl until smooth.
- In a separate bowl, sift the flour, baking powder, salt and nutmeg together. Add this to the sour cream mixture and stir until even blended. Stir in the melted butter (the batter will be thick).
- Preheat vegetable oil to 375 ºF (190 ºC) in a tabletop fryer, or in a deep pot over medium high heat (fill the pot with 2 inches (5 cm) of oil). Use a small ice cream scoop to make golf ball-sized scoops of batter and carefully drop 4 to 6 doughnut holes into the oil. Fry for 4 to 5 minutes, turning halfway through cooking. Lift the cooked doughnuts onto a cooling rack over a tray to drain and cool while repeating with the remaining doughnuts.
For the glaze, whisk the egg white lightly to loosen and then whisk in the vanilla and icing sugar (if the glaze is thick, you can whisk in a little water).
- Dip each cooled doughnut holes into the glaze to coat, shake off excess glaze and then roll into the coconut until completely covered. Return the dipped doughnut holes to the cooling rack to set for an hour before serving.
The doughnut holes are best enjoyed the day they are made.