Asteroids, or minor planets, are leftover building blocks of the terrestrial planets, and the largest of these (i.e. Ceres, Vesta, Pallas) are best described as intact planetary embryos. In the Solar System, we indirectly measure their composition by studying meteorites. Over the last several years, evidence has accumulated that strongly indicates we are witnessing metal-rich debris disks that result from the tidal destruction of large asteroid analogs at white dwarf stars. Analogous to the rings of Saturn, these closely-orbiting disks gradually fall onto the star and contaminate the otherwise pure H or He atmosphere. The white dwarf thus distills the planetary fragments into their constituent elements, and provides powerful insight into the mass and chemical structure of the planetary matter, including the potential to identify water. These studies provide information that at present can be acquired no other way: the frequency and bulk chemical composition of terrestrial planetary bodies around other stars. I will present work to date using this novel approach to the study of exo-terrestrial planetary debris. Currently, there appear to be basic similarities between the composition of Solar System asteroids and extrasolar asteroids, and a few cases where differentiated parent bodies are indicated.