Mandoline – Preferably an Inexpensive Japanese Model
A mandoline is simply a sharp blade mounted on a flat platform, with adjustable screws to set the depth of cut, allowing you to make thin, consistent slices very quickly. Extra attachments allow for a variety of julienne cuts. The inexpensive Japanese models are just as good as, if not better than, the $100-plus European varieties.
I use my mandoline constantly, for dishes like this Persimmon Carpaccio or the garnishes for these cold Korean Noodles. It saves a ton of time and makes cuts far more consistent and beautiful than I ever could with my knife.
You might also like to buy a Kevlar kitchen glove to keep your fingers safe from the blade.