Rinse the sabudanas at least seven to eight times or until the water is almost clear. Rinsing allows to get rid of the extra starch in the sabudana. Place it in a large bowl.
Lightly beat the yogurt and add it to the sabudana. Add water to the sabudana until the water is at the same level as the sabudana and mix it gently. After two hours check the sabudana. If there is absolutely no water at the bottom of the bowl and the sabudana pearls are still hard, add one or two tablespoons of water. Preferably soak the sabudana overnight or at least for five hours.
Test the sabudana pearls between your thumb and forefinger for readiness. It should be soft but not crumbly.
Coarsely ground the peanuts in a food processor and set aside.
Keep all the ingredients ready before cooking.
Place the heavy, rounded bottom pan on the stove. Turn the heat on at medium high and add the ghee or oil. Once the oil is hot, add the cumin seeds. Let them sizzle for two seconds and then add the green chilies and curry leaves, if using. Adjust the heat to prevent the spices from burning. Let the spices sizzle for two more seconds.
Add the potatoes and mix them with the spices. Reduce the heat, cover the pan and let the potatoes cook for 5-7 minutes or until they are soft, but not mushy.
Increase the heat to medium high and add the sabudana, peanuts, and salt. Mix the mixture well and continue to sauté it until the sabudana pearls turn translucent and shiny. Add the sugar and mix well. Then turn the heat off. The sabudana pearls should be soft and slightly chewy but not sticky.
Remove it in a serving bowl. Add the lemon juice and garnish with the cilantro and coconut. Serve it warm.
