How to Make It
Cut banana peppers into rounds to equal 2 1/2 cups, removing seeds when possible. (If some seeds remain, it's okay.) Place in a heatproof container.
Bring vinegar, sugar, and salt to a rolling boil in a saucepan over medium-high, stirring occasionally, about 2 minutes.
Pour hot vinegar mixture over banana peppers, stirring to make sure most are submerged. Let cool to room temperature, about 30 minutes. Cover and store in refrigerator up to 1 week.