It is made just like a regular pie, except bigger and better.
Slab pies are made in a rimmed baking sheet (also called a jelly roll pan) so they are slightly shallower than standard pies and can feed more people.
The result is a slice with a truly spiritual ratio of crust to filling.
Here are some recipes to get your started down the road to enlightenment:
Get the recipe. Taro root looks like a potato, basically, and cooks the same way but has a more interesting nutty flavor. You can find it at specialty grocery stores and probably also at Asian grocery stores.