1. Slice 6 peppers in half lengthwise. Arrange halved peppers, remaining peppers, and garlic in a 1-quart glass jar, or divide among 4 (8-ounce) jars.
2. Combine vinegar, sugar, and salt in a small saucepan over medium-high heat. Cook 4 minutes, stirring occasionally, until sugar dissolves. Pour vinegar mixture over peppers. Cool to room temperature. Cover; refrigerate at least 1 week.