Wash the raw mangoes thoroughly and wipe them.

Cut each mango in half, remove the pit, and chop into small cubes. Rinse the pieces once again and drain well.

If there is good sunlight, spread the mango pieces on a clean cloth or plate and keep them under the sun for a day. If sunlight isn’t available, you can place them under a fan for a day or leave them overnight to dry. Make sure they are completely moisture-free before using.

Start by dry roasting the whole red chillies in a hot pan or kadai. Remove and set aside on a plate.

In the same pan, dry roast coriander seeds, cumin seeds, and fennel seeds together until aromatic. Transfer them to the plate.

Next, dry roast the fenugreek (methi) seeds separately and set aside.

Lastly, while the pan is still hot (with the gas turned off), add the mustard seeds. Let them heat slightly, then remove and set aside.

Let all the roasted spices cool down completely. Once cooled, grind them together coarsely — not into a fine powder.

In a large mixing bowl, add the dried mango pieces and salt.

Then add the turmeric powder, coarsely ground spice mix, kalonji seeds, ajwain, extra fennel seeds, hing, red chilli powder, Kashmiri red chilli powder, and mustard oil. Mix everything thoroughly until all mango pieces are well coated with the masala.

Store the achar in a clean, dry glass or ceramic jar. Keep the jar in the sun whenever sunlight is available. If not, you can also keep it at room temperature — just remember to stir the achar once a day with a clean, dry spoon.

The mango pickle will be ready to eat in about 15 days. The flavor will deepen and get better with time. Always store it in an airtight jar.

If you're making it in large quantities or want to avoid any chance of spoilage, refrigerate the achar after it's ready.

Tip: Always use a clean and dry spoon while serving to keep your achar fresh and safe for a long time.