Pretty pink pickled onions pack a lot of pucker. (Say that five times fast!)
Slice onion into thin strips. Place sliced onion in medium bowl.
In small saucepan, combine vinegar, lime juice, sugar, and salt. Bring to boil over high heat. Turn off heat.
Carefully pour vinegar mixture over onion (ask an adult for help—mixture will be VERY hot). Let mixture cool completely, about 30 minutes.