Select fresh and crisp peppers, discarding any soft or diseased ones.
Wash the jars and lids; sanitize them in boiling water.
Get the canner heating up on low heat.
Rinse the peppers in cold or lukewarm water.
Make 2 slits in each pepper; remove cores and seeds.
Pack one or two garlic cloves and one tablespoon oregano into each jar.
Pack peppers tightly into jars, leaving 1-inch headspace.
Combine vinegar, water, salt, and oil; bring to a boil and simmer for 5 minutes.
Fill each jar with the hot liquid, ensuring the oil is evenly distributed.
Wipe the jar lip clean and add the lids, sealing them snugly.
Process jars in a boiling water bath for 15 minutes for pints.
Remove jars and let them cool in a draft-free place.