How to Make It
Pack sliced sweet peppers, red onion, and jalapeño into a 1-pint heatproof jar. Add garlic, lemon slices, and thyme sprigs.
Bring rice vinegar, sugar, and kosher salt to a boil in a saucepan over high, stirring until sugar dissolves.
Pour mixture over vegetables in jar. Let stand until completely cool, 1 hour. Seal jar; refrigerate up to 2 weeks.