It is always a pleasure to discover a great new restaurant — and even more so when "new" means a lot more than just "recently opened." L'As is a small place with a young crew and a location that is easy to overlook. But since opening in early February in the backstreets of Minami-Aoyama, it's been generating the kind of enthusiastic word-of-mouth buzz that bigger names in flashier areas would give their iPads for.