Wash and slice peppers into ¼-inch rings. Keep seeds for extra heat or remove for milder flavor.
Sterilize two pint-sized mason jars by boiling for 10 minutes or running through a dishwasher hot cycle. Dry completely.
In a medium saucepan, combine vinegar, water, salt, and sugar. Bring to a boil, stirring until dissolved.
Pack each jar with pepper slices, 2 garlic cloves, and a sprinkle of peppercorns (plus optional seeds).
Pour hot brine over peppers, leaving ½-inch headspace. Remove air bubbles with a chopstick or skewer.
Seal jars with lids and let cool to room temperature.
Refrigerate for at least 24 hours before serving. Store in fridge for up to 1 month.