Prepare the Onion: Peel the large red onion and slice it thinly. For even slices, you can use a mandolin, a food processor, or a sharp knife, depending on your preference and available tools.

Mellow Out the Onion (Optional): If you find raw onions too intense, you can mellow out their sharpness before pickling. Place the sliced onions in a colander and pour boiling water over them. Let them drain and cool for a minute before proceeding with the pickling process. This step helps to soften the flavor while still preserving the onion’s crunch.

Make the Pickling Brine: In a medium saucepan, combine the apple cider vinegar, water, minced garlic, and salt. If you're using raw honey or maple syrup, add it in as well. Stir the mixture over medium heat until the honey or syrup is fully dissolved, and the liquid is warm but not boiling.

Add Optional Herbs:If you'd like to infuse your pickled onions with additional flavor, add the sprig of rosemary or thyme and the bay leaf to the saucepan. Let the brine simmer for another minute to allow the herbs to release their flavors.

Combine Onions and Brine: Place the thinly sliced onions into a clean glass jar. Pour the warm brine over the onions, ensuring they are fully submerged. If using the optional herbs, add them to the jar as well. Use a spoon to press the onions down and remove any air bubbles.

Let the Flavors Meld: Allow the jar to cool to room temperature before sealing it with a lid. Once cooled, place the jar in the refrigerator. The onions will be ready to eat in about an hour but will develop a deeper flavor if left to pickle for at least a day.

Store and Enjoy: Store the pickled onions in the refrigerator. They should keep for up to 2 weeks. Use them to add a tangy crunch to salads, sandwiches, tacos, or any dish that could use a pop of acidity.