Heat the mango slices in a pan with small amount of water to make them soft. Add the sugar and mix well. Tie garlic, ginger, red chilli powder and garam masala powder loosely in a muslin cloth and place in the pan. Mix well and cook, on medium heat, till it reaches a jam consistency.
Add vinegar, salt and cook for five minutes. Remove the spice bag, cool and store the chutney in sterilised glass bottles.