How to cook Sarkaraivalli Kilangu Sweet Potato

The US Sweet Potato is entirely different from our sarkarai valli kilangu. So i was longing for our exact sarkarai valli kilangu. One day when we went to Korean supermarket i saw this in huge quantity with the name of Korean yam or Korean sweet potato. I thought of sharing with you guys. It tasted exactly as South Indian sarkarai valli kilangu and I love to have this Kilangu with ghee and sugar. For this cook it in pressure cooker with enough water for 2 hisses. If they are small 1 whistle is fine otherwise they turn mushy.