1. Peel and chop the mangoes. Peel and roughly chop the onion and garlic. Place onion and garlic in the bowl fitted with the ultrablade knife. Mince at speed 11 for 10 seconds. Scrape down the sides of the bowl.
2. Add all remaining ingredients and mix at speed 6 for 10 seconds. Launch the P2 simmer program at 210°F for 45 minutes, without the stopper.
3. Pour the mixture into sterilized jars. Cover and refrigerate for up to 3 weeks or freeze for up to 1 year.