But tuna is often frozen, too, not necessarily to make it safe, but because global consumption of sushi continues to rise. Frozen fish usually costs about half as much wholesale as fresh. And some cuts, like the prized fatty toro, are not always available fresh. Naomichi Yasuda, the owner of Sushi Yasuda, the acclaimed sushi restaurant in New York City, said he imported fresh tuna but froze it himself, selling it for $10 a piece.''American customers don't want to hear that something is out of season'' he said with a shrug. ''People want toro every day.''At the Elizabeth, N.J., warehouse of True World Foods, a manager, Ken Kawauchi, recently readied a room-size freezer to receive eight more tons of premium tuna frozen with sophisticated technology that chefs say preserves the texture and flavor of the fish.''This product is better than fresh,'' he said. ''We start freezing it almost before it's dead.''At 76 degrees below zero, you can feel your hair follicles freeze. A 20-pound chunk of premium bluefin tuna is rock hard and cold enough to burn a blister on your finger.

But all it takes is a band saw, 10 minutes and a bowl of warm water to produce deep red, dewy slices of the finest sushi money can buy, the same toro served at Manhattan sushi shrines.Sabine Marangosian, who works in Midtown Manhattan, said she ate sushi ''at least once a week.'' ''I guess I would understand that some sushi is frozen,'' she said. ''But I would hope that's not the case at Nobu.''But Shin Tsujimura, the sushi chef at Nobu, closer to Wall Street, said he froze his own tuna. ''Even I cannot tell the difference between fresh and frozen in a blind test,'' he said.Even Masa Takayama, whose sushi temple Masa, in the Time Warner Center, charges a minimum of $300 to worship, said he used frozen tuna when fresh is unavailable. Many sushi bars, in Japan and elsewhere, routinely use frozen fish when fresh is unavailable or more expensive than the market will bear.''In Japan,'' Mr. Kawauchi said, ''50 percent of the sushi and sashimi is frozen. Only my American customers are so concerned with fresh fish.''

Americans have clearly overcome the initial resistance that greeted sushi when it was widely introduced nationally in the 1980's.The number of Japanese restaurants across the country has steadily increased in the past five years, according to the National Restaurant Association. where to buy raw sushi salmonAnd that number does not include the supermarkets, delis, cafeterias, and Costco stores where sushi can now be purchased.A.F.C. Sushi, a Los Angeles-based sushi franchiser, has more than 1,800 outlets nationwide. buy fresh sushi onlineIt already supplies the Staples Center, in Los Angeles; free online sushi making gamesFlorida State University, in Tallahassee, Fla.; healthy things to order at sushi restaurant

and the United States military, which buys sushi for its commissaries. Although the company's Web site refers to ''fresh sushi,'' A.F.C. uses only frozen fish in its products.According to wholesalers like Dave Rudie, a pioneering sushi supplier in California who sells both fresh and frozen fish, more and more frozen fish is being served as sushi here.Mr. Rudie said that worldwide, some sushi products are virtually always frozen. ''Ninety percent of shrimp, of course,'' he said, The salmon roe ''and octopus, 99 percent. And you definitely want all your salmon frozen, because of parasites.''The Food and Drug Administration does not enforce the frozen-fish rule, leaving that to local health officials. The agency says sushi fish can be frozen either by the wholesaler or in the restaurant, and each party likes to believe that the other is taking care of it. ''I always assumed that the fish is frozen at some point before I get it,'' said Jack Lamb, owner of Jewel Bako in the East Village in Manhattan, ''but just for a minute, like an X-ray.''

Ian MacGregor, whose wholesale business, Lobster Place, supplies the sushi hot spot Geisha, in Midtown Manhattan, said he had heard countless euphemisms for frozen fish in restaurants. ''Fresh-frozen, re-freshed, flash-chilled, take your pick,'' he said. But ''superfrozen'' fish seems to be in a category by itself. Many top sushi chefs are finding that fish frozen to about 70 degrees below zero, instead of the commercial standard, usually 10 below, can stand up to their rigorous standards.Tuna, one of the most expensive sushi fish in the world, has been the test market for superfreezing.Freezing technology that truly preserves the quality of fresh fish is relatively new, said Eric Graham, managing director of ColdWave Systems, a global seafood shipper.Developed by the Japanese fishing industry in the 1990's to preserve the catch on long trips, superfreezing can reduce the core temperature of a 500-pound tuna to minus 70 degrees in about a day and a half. Packed in artificial snow ground from dry ice and surrounded by liquid nitrogen, that fish can be preserved with no decomposition for as long as two years.''

It's an amazing product,'' said Mr. Lamb, who recently bought a medical freezer, designed to store transplant organs, to keep tuna in his restaurant's basement.But in places like Los Angeles, where the Japanese Restaurant Association of Southern California has considerable local support, frozen sushi is not a popular notion.''We try to recognize that sushi has been made with fresh fish in Japan for thousands of years,'' said Terrance Powell, chief environmental health specialist for Los Angeles County.Mr. Powell and his team of 150 inspectors have held food safety classes for sushi restaurant operators in Japanese, Korean, Thai and Vietnamese, but he concedes that most operators, knowingly or not, are probably not serving only frozen fish. ''Frankly,'' he said, ''warm sushi rice that sits out for hours is a bigger public health threat than raw fish.''Chicago is a good place to find quality sushi bars and restaurants. I really enjoy going out for a fantastic sushi meal, but only on occasion since it can be quite pricey.

Last week, I got really psyched to roll my own sushi, and went out on a quest to find all of the right ingredients. If you have the backbone of what you need to roll your own (sushi mat/roller, sushi rice, rice wine vinegar, wasabi powder, nori sheets, pickled ginger), then making it yourself is fairly inexpensive and a lot of fun. I started my quest of finding ingredients in Uptown, at the intersection of Argyle and Broadway. This is known as Little Vietnam (I know, a far cry from the sushi homeland of Japan, but I swear they have almost everything you need to make sushi). I went to two stores, Hoa My Market on Argyle Street and Tai Nam on Broadway (they’re less than a five minute walk from one another). Both stores carry five to twenty pound bags of sushi rice (I think I paid less than $3 for a five pound bag), a ten pack of nori sheets for less than $2, large bottles of rice wine vinegar for less than $3 and wasabi powder for around $3.50. The pickled ginger, however, I could only find at Hoa My Market, where they had both the pink pickled ginger and the yellow pickled ginger.

The difference between the two is that the pink ginger is slightly younger than the yellow. Some brands use beet juice to dye the ginger, if it is too mature during the pickling process. Hoa My doesn’t carry sushi mats, but Tai Nam had them for super cheap (I had to ask for assistance to find these, as they were hidden somewhere near the back of the store). Between both stores, I spent around $20 for the basic sushi ingredients that I needed. As for the fish, I chose to go to the trusty Whole Foods Market in Lakeview. I’m a little unsure of purchasing fish at either of the markets previously mentioned, especially if I’m eating it raw (I’m pretty sure they don’t carry sushi grade fish at Hoa My or Tai Nam). Here’s the thing with Whole Foods and sushi grade fish - they don’t normally carry sushi grade, but they do take orders and can bring in whatever type you’re looking for, within reason. Unfortunately, I wasn’t aware of this until the guy behind the counter told me.

By this point though, I was on a mission and wasn’t going to wait a day or two for a fish order. The next step was to sweet talk the employee at the sushi counter in the prepared foods section of the store. At the counter they had pre-packaged sashimi (thin slices of raw fish, not prepared into a sushi roll) priced a little under $10. Instead of buying that, I kindly asked the lady behind the counter if she had any fish that wasn’t sliced into sashimi and that she’d be willing to weigh out for me and sell. This lady was my hero for the day, because she sold me a lovely quarter-pound piece of tuna for a couple dollars less than the sashimi package. Next time I go to buy fish, I probably won’t do this again (I don’t want the people at Whole Foods to catch on), but instead I’ll just order it ahead of time. There are also other local options such as Hooked on Fish and Wixter Market. As for the vegetables, I picked up a small cucumber, daikon radish and an avocado while I was at Whole Foods.

I would’ve liked to buy some asparagus, but it’s not the right season for that. After several hours of shopping, I was finally home with all of the ingredients I needed to roll sushi (including a couple bottles of sake, because you shouldn’t eat sushi without it). I made a spicy tuna roll (diced tuna fish mixed with a little sesame oil, Sriracha hot sauce, and sliced green onion), a tuna inside out roll (which I topped with a mixture of Sriracha and mayonnaise to add a little heat), and a couple of veggie rolls. Rolling sushi at home is a really fun activity and great practice if you want to look like a pro while entertaining in your home. Now that my kitchen is fully stocked with the backbone ingredients, it will be an affordable option to make more often. I would go through the process of making sushi, from the rice to the rolling, but The Chopping Block's Owner/Chef Shelley Young covers that in her How to Make Sushi at Home post. Plus, we offer sushi classes several times a month at both of our locations.