Peel and grate the raw mangoes using a grater. Measure out 2 cups of grated mango and set aside.
In a thick-bottomed pan or kadhai, add the grated mango, turmeric powder, and salt. Mix and cook on medium heat for 1-2 minutes.
Add sugar and let the mixture cook. Stir continuously until the sugar dissolves and the mixture starts bubbling.
Add cumin seeds, dried red chilies, cloves, cinnamon stick, and peppercorns. Mix well and continue cooking until the sugar reaches a one-string consistency (check by stretching a drop of syrup between your thumb and finger).
Once it reaches the desired consistency, add red chili powder and cook for 1-2 more minutes.
Turn off the heat and let the Chundo cool completely.
Once cooled, transfer to a clean, dry glass jar and store in the refrigerator. It keeps well for up to a year.