If you're looking to bring a little four-star dining home, skip the caviar and buy a chunk of sashimi-grade ahi tuna. It currently retails for $16.95 a pound at Tokyo Fish Market and $19.95 at Berkeley Bowl. The ahi you'll get is high-quality yellowfin tuna from the deep Pacific. (Tonier, finer bluefin tuna is almost impossible to purchase retail in the United States -- the Japanese snap it up for prices much higher than most Americans would pay.) Drizzle thick slices with a fruity olive oil, gray sea salt, and finely chopped lemon zest and parsley. Coarsely chop it and mix with minced shallots and capers, a little Dijon, and a splash of Worcestershire sauce for an almost classic tuna tartare; for a more subtle, Eastern tartare, combine chopped ahi with a little sesame oil, tobiko caviar, green onions, and Japanese hot pepper. Or roll a block of fish in salt and cracked peppercorns and quickly sear the edges for the pièce de résistance
of a salade niçoise
. The silky, sweet flesh always tastes like more than you spent on it.