Hot-pack method
Wash and rinse half-pint canning jars and keep hot. Prepare lids according to the manufacturer’s directions.
Wear plastic or rubber gloves while handling raw green mango. Wash produce. Peel and cut mango into 1/2-inch cubes, dice bell pepper into 1/2-inch pieces, and finely chop the onion.
Combine all ingredients in an 8-quart Dutch oven or stockpot. Bring to a boil over high heat while stirring to dissolve the sugar. Reduce heat and simmer for 5 minutes.
Fill hot solids into hot half-pint jars, leaving 1/2-inch headspace. Cover with hot liquid while maintaining 1/2-inch headspace. Remove air bubbles, adjust headspace, wipe rims, and apply two-piece lids.
Process half-pints in a boiling-water canner for 10 minutes at 0–1,000 feet, 15 minutes at 1,001–6,000 feet, or 20 minutes above 6,000 feet. Cool undisturbed for 12–24 hours and check seals.