Wash and dry the pepperoncini, then slice them in half lengthwise.

In a saucepan over medium heat, combine the vinegar, water, sugar, and salt. Stir until dissolved and bring to a gentle simmer.

Add the smashed garlic cloves and oregano to the brine; let simmer for about five minutes until fragrant.

Pack the pepper halves tightly into sterilized glass jars.

Pour the hot brine over the packed peppers, ensuring they are fully submerged with half an inch of headspace.

Once cooled slightly at room temperature, seal jars with lids and refrigerate for at least three days before enjoying.