RESTAURANTS : <i> Carpaccio: The Raw Truth</i>

C arpaccio is hot. Well, actually it’s cold; but the smooth, cool, paper-thin slices of the finest raw beef, slick with extra-virgin olive oil, have found their way onto menus from Spago to Rex and nearly every restaurant on Melrose. It’s become so trendy that Marie Callendar’s feels compelled to sling mudpies at the dish in ads that proclaim, “We can’t pronounce carpaccio either.”

Blame it on the contessa . . . Contessa Amalia Nani Moceniego, that is. She was bored and rich and a finicky eater.

“She could eat only a few things, among them raw meat,” remembers Arrigo (Harry) Cipriani, proprietor of Harry’s Bar, the infamous Venetian watering hole immortalized in Hemingway’s novel “Across the River and Into the Trees.” “And she was sick and tired of tartare. “

“My father (the late Giuseppe Cipriani, who first opened Harry’s),” Cipriani said from Venice in a phone interview, “sliced a very thin filet of tenderloin for her and put a little bit of sauce on top, what we called a universal sauce--it’s good for fish and it’s good for meat. Then he said, ‘Try this, countess,’ and she liked it.” So did other restaurant owners. Soon after the contessa’s visit (which Cipriani thinks was around 1956 or 1957), restaurants all over Italy began to serve variations of the raw meat dish that Giuseppe Cipriani named carpaccio , for the Renaissance-era painter whose work was being exhibited in Venice at the time of the contessa’s visit. (Art history books often pair Carpaccio with the painter Giovanni Bellini; the two are paired in the food world as well. Giuseppe Cipriani also invented the Bellini cocktail, a drink made of peaches and champagne. Carpaccio and a Bellini make a good light lunch.)

One thing about carpaccio : No two chefs prepare it the same way. Some just drizzle olive oil on top; some prefer a heavier mustard and Worcestershire sauce. Some don’t even bother to use beef. According to Locanda Veneta chef Antonio Tomassi, horsemeat carpaccio is common in Europe (“It’s very sweet and tender,” he says).

Closer to home, tuna carpaccio and salmon carpaccio are featured on most trendy menus. Silvio Di Mori of Tuttobene on Fairfax Avenue sells more fish carpaccio than beef. For a while, Di Mori even experimented with a carpaccio of vegetables--thinly sliced eggplant, squash, carrot, zucchini and mushrooms arranged like a flower. “I tell you it was very, very good,” Di Mori says. “It had a nice coloration. But people would only order it once every two days or so.”

Harry Cipriani is convinced that his father’s version is the best. “The only true carpaccio in the United States,” Cipriani said emphatically, “is from Bellini in New York.” (Bellini is Cipriani’s American version of Harry’s.)

Actually, Cipriani thinks so highly of Bellini’s carpaccio that he prefers it to the one served at his own Harry’s Bar in Venice. He said, “The meat in the United States is so much better than it is here.”