In a glass jar, spread some of the cubes and sprinkle some salt over it. Add a few more cubes and make another layer. Sprinkle some more salt. Repeat the process for the remaining mango cubes and keep aside.
Powder the mustard seeds and red chillies to a fine mixture.
Add hing, and turmeric and mix well. Do not add any water while powdering the spices.
Add the powdered spices to the mango-salt mixture and mix well with the help of a long spoon.