Peel and cut mangoes into thick slices. Marinate with salt and leave till much liquid is drawn out from the mangoes. Rinse mangoes thoroughly and sun till dry. Pour a bottle of white vinegar into a stainless steel pot and add in a bottle of plain water. Add in sugar and cook over fire till sugar dissolves. Adjust sugar according to your preference and throw in 2 red chillies with seeds. Cool and pour over mangoes in a glass jar. Keep in a cool dark place for at least 1 week before consumption.