Clean and core apples. Then, dice them into bite-sized cubes.
Add salt to the apples as soon as possible to prevent browning. Keep aside for some time (less than 5 minutes).
Heat oil in a pan / kadai and throw in mustard seeds.
When the mustard seeds splutter, add curry leaves. Sauté till the leaves are fried but not burnt.
Remove the kadai from flame / heat.
Add the spice powders and stir vigorously for 5 seconds.
Toss in the diced apples and mix well to coat the apple pieces in the spice mixture.
Add vinegar. Taste and add salt, if required.
After the pickle cools down, transfer it to a dry and airtight jar.