Peel the yam and cut it into small cubes.
Boil the yam with gooseberry in a pressure cooker for 3-4 whistles. You will know the yam and Indian gooseberry is cooked once you squeeze it a little and it is easily mashable and tender like boiled potatoes.
Note: Yam is a very spicy vegetable and it needs to be balanced with the sourness of Indian gooseberry. If you do not have Indian Gooseberry available you can substitute with Tamarind. But this step should not be missed as it can give an allergic reaction. If you do not have a pressure cooker, please boil these ingredients in hot boiling water until tender.
Remove the cooked Yam and Indian Gooseberry and keep in sunlight (Preferably between 10 am to 2 pm) for two hours for it to dry.
Cut the Radishes in circles and keep it in sunlight for two hours in a different open vessel.
After two hours, mix Radish, Indian Gooseberry, and Yam together in a big open vessel.
Grind the spices together with salt as per your taste.
Mix the ground spices with the yam and radish mixture. After giving a good mix, add mustard oil and mix some more until each ingredient is well coated.
Put this pickle back in sunlight for the entire day and it is ready to eat the next day!
Enjoy it with Indian flatbread with ghee, Dal and Rice or plain simple Indian Khichri.