The latest thing heating up the U.S. is thin, hot and Italian. No, it's not the sexy new "It" girl. It's grilled panini.

Panini, which means "sandwich" in Italian but in the U.S. refers to a hot, pressed sandwich, is quickly becoming a lunchtime favorite at delis and cafes around America.

"How wonderful of an addition to the culinary menu of the USA," said Domenic Seminara, an Italian native who has been selling panini presses since the mid-80s. "Just like cappuccino and pasta in the '80s, granita in the '90s, panini is the food of the new millennium."

Sales at Seminara's Arlington, Texas- based company have gone into "high gear" in the last three years.

"I'm getting hundreds of e-mails a week from all over the world," he said.

Indeed, the warm sandwiches seem to be popping up everywhere. At Liberty Deli in midtown Manhattan, the panini presses were brought in only three months ago, said manager Sam Chand. And Caffe de l'Universite at New York University started serving the sandwiches just three weeks ago, said manager Dony Ravi.

"They're the talk of the town now," said Chand.

Despite all the attention, Seminara said his beloved sandwich is still misunderstood.

"You're supposed to display the meats in a small deli case. Then you let people mix and match. That's how it's done in Italy," said Seminara, who has over 200 panini recipes on his Web site.

Instead, most U.S. delis offer set combinations on a menu that almost always includes the Copenhagen, made of turkey, cole slaw, Swiss cheese and Russian dressing, and the Monte Cristo, which consists of ham, smoked turkey, Swiss cheese, cheddar cheese, tomato and honey mustard on European flat bread.

Frank Soto, manager of Café Baci in Chicago, agrees with Seminara that these bulging sandwiches break the thin-and-simple panini protocol.

"We haven't conformed to recent trends. We serve real panini," he said.

But what is "real panini"? Seminara described it as something that will please a woman.

"Let's say a lady from your office comes to my place to eat. When she comes back, her co-workers will say, 'What did you have?' If she says, 'I had a sandwich,' the conversation ends right there," he said. "But if she says, 'I had a panini,' people will say, 'Oh what's that?' And she'll say, 'Oh it's so wonderful, toasted and hot with nice ridges on the bread."

But the sandwiches don't technically need to be hot, he added.

"You can just grill a boneless piece of pork or chicken and put it in bread," he said.

Despite the larger American versions, Seminara speculated that one reason for panini's popularity is its delicate size compared to sandwiches at certain chain shops.

"A Subway sandwich is a big mother. At Subway you fill it up at the lowest price like at the gas station -- you fill your belly without caring for the taste," he said. "Panini has slimmer pieces of meat and cheese in the middle."

But everyone is not ready to forget their old standbys. Investment analyst Matt Abramcyk, 23, said the chicken caprese panini he recently had at a New York City deli was "terrible."

"They tried to get away with toasting bread that wasn't fresh to begin with," he said. "I had one in Italy and it was a lot better. But for value for my money I'll go to Subway nine out of 10 days a week."

Yet New York City resident Emily Kramer, seen eating a prosciutto-and-mozzarella panini at Liberty Deli, said it was the sandwich's slenderness that sold her on it.

"I don't feel as guilty," she said.

In the end, Seminara said, Americans will be seduced by panini just as they have been by other Italian delicacies.

"It's a sandwich with romance, just like cappuccino is coffee with romance."