Wash the mangoes and cut off the tops. Chop the mango in half lengthwise and remove the seed. Cut up the mango lengthwise. The mango has to be young enough to do this and can't be too full. Add the salt, toss and leave over night. Drain the salty water. Dry with a towel. Spread a cloth on the roof and place mango to dry.
Note: This may take about two to three days depending on the weather. If you don't have the hot sun like I have you can use a solar drier, a dehydrator or put it in the oven to dry, set at 120 -145 degrees F. Make sure to check it occasionally!
Heat the oil over a medium flame. Cut up the hot pepper. Add the pepper and garlic to the oil. Cook for about 1 minute. Add the mango and amchar masala. Allow to cook for about 2 minutes stirring occasionally. Turn off the flame, add mustard oil and salt (the mustard oil is used as a preservative).
Allow to cool and store in a large bottle in a cool place. After putting it in the bottle we placed the mango anchar back in the sun to dry a little more.