In a large saucepan, combine vinegar, sugar, lemon juice, mustard seeds, turmeric, ginger, and garlic. Bring to a boil, then simmer until sugar dissolves.
Add pineapple and jalapeños, cooking over medium heat until pineapple is tender and the mixture is syrupy, about 20 minutes.
Sterilize jars and lids, then ladle the mixture into jars, leaving ¼ inch headspace. Seal and process in a boiling water bath for 10 minutes.
Cool jars completely, check seals, and store in a cool, dark place.
Prep Time: 20 minutes
Cooking Time: 30 minutes
Total Time: 50 minutes
Kcal: 100 per serving