@simrin-- It would be hard to find yacon products in regular grocery stores, but definitely check out organic groceries.
I found yacon herbal tea at our organic grocery. I remember asking the employee about what yacon was. Some months later, I also spotted fresh yacon at the farmer's market in Oregon. I didn't pick up any as I had no idea what I would do with them.
I do wish I had tried them though. I didn't know that they are so tasty and healthy! I will definitely buy some next time. I have a cousin who is vegan, I'm sure she would be happy to use it if I don't.