To the uninitiated, chef Joshua Hebert's contemporary American restaurant concept may take some getting used to. He calls it "improvisational cuisine," and in the same way that a jazz musician gets in a groove and spins off an impromptu melody, Hebert plays around with ingredients in unexpected, unpredictable ways. And while some of the Valley's top chefs are constantly tweaking their menus based on what's in season, Hebert eschews a menu altogether. Instead, guests guide their dining experience with a checklist indicating how many courses they'd like, which featured meat and seafood appeals (or doesn't appeal) to them, whether they'll eat raw foods, and any other preferences. (If it's reminiscent of omakase dining at a sushi bar, where you trust the chef to feed you well, that's because Hebert did a stint at Tokyo's Miyako Hotel several years back.) Beyond that, dinner is a series of tasty surprises — scallop carpaccio with radish, pickled grapes, and squash blossom pesto; foie gras with citrus coulis and spun sugar; mushroom-braised veal with morels, peas and fresh mint. Seafood is Hebert's forte, but he's also fond of the exotic, like roasted kangaroo. To be sure, the Posh kitchen can handle the most finicky diners, but the customers who'll have the most fun will simply leave their meal in Hebert's capable hands.