Prepare the Peppers: Wash and dry the peppers. Slice into rings or leave whole, making a small slit in whole peppers to allow the brine to penetrate.
Sterilize Jars: Wash and sterilize glass jars by boiling them in water for 10 minutes.
Make the Brine: In a saucepan, combine vinegar, water, sugar, salt, peppercorns, mustard seeds, and bay leaves. Bring to a boil until sugar and salt dissolve.
Pack the Jars: Place garlic cloves and peppers into the sterilized jars. Pour the hot brine over the peppers, ensuring they are fully submerged.
Seal and Cool: Add a tablespoon of olive oil if desired. Seal jars tightly and let them cool to room temperature.
Marinate: Refrigerate for at least 24–48 hours before tasting. Flavor improves over time, ideally 1 week.
Serving and Storage Tips
