Peel the mango, slice the fruit from the stones, and finely dice. Peel and finely dice the onion. Add the mango, onion, sugar, spices, vinegar, and salt to a saucepan. Bring to a boil, reduce the heat to medium, and simmer for 45 minutes.
Fill the prepared, sterilized jars to the brim with the chutney. Seal tightly, and cool completely. Store in a cool, dark place.