Combine the mango, apple, onion, brown sugar, vinegar, garlic, chilli and salt in a large, heavy-based saucepan over medium heat. Bring to the boil, stirring occasionally. Reduce the heat to medium-low and simmer gently for 1 hour, or until the excess liquid evaporates and the chutney is thick.
Stir in the sultanas and allow to stand for 15 minutes. Ladle the hot chutney into clean, warm, dry jars. When cold, label and date the jars and store in a cool, dry, airy cupboard.