Line baking sheet with foil. Using fingertips, mix sugar and citrus peels in a small bowl until sugar is moist. Stir chocolate in small bowl set over saucepan of barely simmering water until melted and smooth. Remove from over water.
Holding 1 strawberry by stem end, dip 2/3 of berry into chocolate; shake excess back into bowl. Turn berry dipped end up and sprinkle with citrus sugar. Place on prepared sheet. Repeat with remaining berries, chocolate, and sugar. Chill until chocolate sets, about 30 minutes.
