The best restaurant for sushi is Shibuya in Calabasas.  It's a tiny little place next to the post office but the food is fresh and yummy.  Be sure to order the mushroom and asparagus appetizer, it is over the top in flavor.  The seared toro is also one of our favorites.  The wait can be long in the evenings, so eat a cracker or two before you leave the house, the wait is worth it!