Wash and dry the mangoes completely. Moisture can spoil the pickle.
Cut the mangoes into small cubes or slices, leaving the skin on if you like the texture.
Salt the mango pieces and leave them in a bowl for about 2–3 hours to release some moisture.
In a separate bowl, mix:chilli powderturmericmustard seedsfenugreek seedsgarlic (optional) Heat the oil until hot but not smoking, then let it cool slightly.
Add mango pieces to the spice mixture and mix well.
Pour the warm oil over the mango mixture and stir until everything is coated.
Transfer to a clean glass jar and press down so the oil covers the mango.
Leave in a warm place for 3–5 days, shaking or stirring the jar daily.