In a medium saucepan, heat the 1 tablespoon olive oil over medium heat. Add the ½ cup diced red onion and ½ red bell pepper and sweat the vegetables until they're softened but not browned, stirring occasionally.
Add the ¼ cup apple cider vinegar and ¼ cup brown sugar. Bring to a boil, then reduce heat and simmer with the lid off the pan for 5-7 minutes or until the the liquid has reduced by half and has become syrupy, stirring occasionally.
Add the 2 cups fresh pineapple, 1 inch knob ginger,½ jalapeno pepper, ½ teaspoon whole mustard seed, ¼ teaspoon ground coriander and ⅛ teaspoon crushed red pepper flakes and simmer for another 5 minutes, stirring occasionally until the jalapenos are softened and most of the liquid has evaporated. Stir in the 2 tablespoons golden rum and cook for an additional 2 minutes. Remove from heat and taste for seasonings. Adjust as necessary.
Store the chutney in a sealed glass jar in the refrigerator for up to a week.
Notes
Store chutney in a sealed container in the refrigerator.