The idea sounds ridiculously simple — chopped up, lightly seasoned raw tuna — but in fact it requires unstinting attention to detail. First, the tuna itself must be of the silkiest, fattiest variety, and the ahi, a Hawaiian word that takes in both the yellowfin tuna and the big-eye, is most prized for its suitability for the highest grade of sushi and sashimi. The fish must be impeccably fresh, the cutting done so that the texture is not mushy, the seasonings delicate so as not to distract from the flavor of the tuna, and the temperature should never be too cold to mask flavor and texture. After that, it’s up to the imagination of the individual chef to make his mark on the dish. One of the best is Andre Guerrero, chef-owner of the hot new MAX in Sherman Oaks, California (13355 Ventura Blvd.; 818-784-2915), where he forms the ahi into small towers tinged with wasabi and tobiko, laced with a little seaweed and ginger, and set with a cucumber salad.

Other restaurants that do ahi up right:

ATLANTA: Joel, 3290 Northside Pkwy.; (404) 233-3500

CHICAGO: Wave, W Chicago Hotel, 644 N. Lakeshore Dr.; (312) 255-4460

NEW ORLEANS: Marigny Brasserie, 640 Frenchman St.; (504) 945-4472