Peel and dice 1 fresh pineapple, into bite-sized cubes. Deseed and dice 1 jalapeno and juice the limes. Set all aside.
Heat 1 cup apple cider vinegar and ¼ cup water in a small sauce pan over medium-high heat. Bring it to a simmer, then remove from heat and pour the mixture into a large mason jar. Stir in 2 teaspoons kosher salt and ¼ cup lime juice. Next, add the diced pineapple.
Add the diced jalapeño and 5 sprigs fresh cilantro. The contents of the jar should be fully submerged in the liquid. Top off with a little more hot water, if needed.
Cover and set it aside on the counter for about an hour. If you're making it in advance, set the jar in the refrigerator overnight.
Video
Notes
To store: Store the pickled pineapple in any airtight glass container in the refrigerator for up to a week.