See Natasha's post. Manioc is "sort of like it" but not exactly. Manioc is more like the yautía and pasty.
Probably any good Mexican store there in Phoenix will carry it.

1. Peel it with a fairly dull knife
2. Rince it
3. Grate it and make fritters by adding a little flour, salt and milk.
4. boil it in salted water and eat with eggs and sauteed onions

enjoy!