The Japanese art of sushi was bound to change once it reached the Americas and American-born chefs and diners took it up. How many aspiring local chefs would put up with the rigors of Japan's decade-long apprenticeship system? And how many eaters here care about that? Those enviable souls who appreciate it and can afford it may pay a hundred dollars or more for an exquisitely artful omakase ("chef's choice") meal at, say, Katsu in L.A., or up to a couple thousand (!) for one at Masa in Manhattan. Most Americans, though, are content to drop in at neighborhood sushi bars for a bite. These local places become community hangouts, and if the neighborhood is lucky, they offer good eating, too.

So residents rejoice when a sushi bar lands in a restaurant-sparse area. I first spotted Zensei a few days after it opened. A crowd was gathered at the dogleg at 30th Street and Upas, a line leading to the entrance of a gray, long-vacant building. Driving by, I made out part of the sign -- Zen-something -- and added up the evidence. "Omigod, omigod!" I squealed like a teenager. "Did you see that? It's a sushi bar! Not a taquería, not a pizzeria. We're gonna have sushi in North Park!" "Did you say sushi?" my boyfriend asked, ducking an SUV that was crowding us on the turn.

A couple of months later, we returned on a damp Sunday, a challenging day for sushi, since there are no fish deliveries on the Sabbath. Zensei's interior is long and narrow, with a sushi bar on one side, a row of tables along the windows, and toward the back, banquettes that can be pushed together for larger parties. Oil paintings by local artists decorate the walls. Hidden in back is a kitchen where the non-sushi items are cooked; en route from the parking lot, you can spy on the chefs working there.

We settled down at the bar, and Monica, our courteous hostess, brought relish plates of wasabi and pickled ginger. A young Latino, Hugo Arreguin, stood behind the sushi counter.

We started, as we always do at a new sushi bar, with an order of uni, sea urchin "roe" (gonads, actually). It's an instant pass/fail test: If the uni is mushy and tastes like iodine, it's too old and we're outta there. But even on Sunday, Zensei's golden-orange lobes were velvety, fresh and briny, and the portion was generous. The rice was excellent, with cohesive grains and a sweetness from seasoned sushi vinegar. Our next choice was ama ebi, "sweet shrimp," presented with the raw bodies and flash-cooked heads on the same plate and garnished with a heap of raw carrot shreds. Most sushi chefs flavor the rice under the bodies -- with wasabi, maybe, or yuzu juice (from a Japanese citrus fruit) -- because these freshwater shrimp are often bland. Hugo left the rice unadorned, so this was the one roll for which I stirred up a soy-wasabi slurry dip.

Meanwhile, a ponytailed young woman a few stools down was doing my job, giving Hugo a "chef interview" as he worked. The owners, Jo-Jo (José Fantos) and Al (Alberto Quintos), "don't cook sushi or really know that much about it," Hugo said. "They were looking for an investment and focused on this neighborhood because Jo-Jo used to live around here, and they realized that what the area needed was sushi." "Right!" chorused Ms. Ponytail and her date. "We walked six blocks in this freezing weather."

That comment made us crave hot food along with the cold sushi rolls -- a bowl of miso soup. The kitchen in back prepares the cooked dishes, including soups, hot sushi-bar appetizers such as "dynamite" and stuffed tempura-fried shiitakes (here called Bombe-Bombs, stuffed with salmon, cream cheese, and a touch of dashi, dried bonito broth). It also offers entrées of tempura, noodles, teriyaki, fish, and chicken katsu (croquettes), including a version with yuzu sauce. The soup proved weak on miso flavor but was well garnished with diced tofu, shiitake shreds, green onion tops, and nori slices. Monica thoughtfully gave us two spoons without our having to ask.

After the uni and ama ebi, we were starting to trust the chef, so we tried a spicy scallop hand roll -- another test. This roll is a rare delight when chefs do right by it, but some chefs omit vital ingredients (e.g., mayo), some plop the scallops on top of the cone instead of mixing them into the rice, and some use slimy scallops. Trainee chefs may roll so ineptly that the cone-bottom oozes rice into your lap. Hugo's version was a layered construction: He laid rice on a sheet of nori, topped it with cucumber sticks, small scallops (of decent quality) mixed with Japanese mayo, and shakes of hot sauce, then rolled the nori into a well-sealed cone. My boyfriend's only complaint was that the mayo was bland. "Almost everybody uses the bottled stuff now, Kewpie brand, instead of making it themselves," he grumped.

Down the counter, Ms. Ponytail's interrogation of our chef continued. Hugo started out making sushi at E Street Alley about eight years ago, learning from the Japanese chefs there. "I learned both traditional and nontraditional styles," he said. "They trained me for about a year. After that they let me start making rolls." He has worked at other sushi bars, including Yokozuna's in Chula Vista and Bamboo Hut in Mira Mesa. Jo-Jo and Al, old acquaintances, approached him to come work for them three years ago, when they began planning for Zensei.

Later, I asked owner Jo-Jo whether "Zensei" was a pun on sensei (Japanese for "teacher"). "From what I understand, it's an old term, used in the early part of the last century," Jo-Jo said. "It means 'the height of prosperity and power.' Japanese who are 50 and older know the term, but younger people have no idea what it means." And the reason the restaurant took three years from planning to opening? "The delay was due to our inexperience. We had to redo the whole interior of the space and also deal with the city about permits. We ran out of money about four times." Jo-Jo said that Hugo's co-chef (on vacation that week), Rocendo Rendón, got his training under the master sushi chef of the Benihana chain and worked at the local Benihana for several years before joining his friends at Zensei. Zensei gets its seafood from the same Los Angeles sushi specialist that supplies the esteemed Sushi Ota and Nobu, among others. (Not coincidentally, Lizard Lounge also buys from them.)

For our first inside-out "party roll," we chose one of the imaginative house specialties, "stuffed tomato," which features spicy scallops and rice wrapped in ruby-red tuna. The flattened globe (cut into handy quarters) looked like a stuffed beefsteak tomato. The ahi was silky, the rice at the center topped with black masago (smelt roe) for crunch and good looks. Next up, we ordered a "rainbow roll" -- a California roll (with sweet crab and avocado at the center) wrapped in slices of ahi, salmon, yellowtail, and avocado. Zensei's version is gigantic and delicious, though standard.

"Isn't it odd that so many sushi chefs in San Diego are Mexican?" Ms. Ponytail asked Hugo. "There's a lot of communities here with a mix of Japanese and Mexicans, like Chula Vista," he answered. "So every day, more and more Mexicans are learning to make sushi."

When I posed the same question to Jo-Jo, he said, "The majority of sushi chefs have to pay their dues. They start off as dishwashers, and if they show that they're interested, then they have to prove themselves and work their way up. That's how a lot of Mexicans get into making sushi...But it doesn't matter to me what race the chef is, because at Zensei, we're not trying to be traditional. Our chefs are really personable and make it a nice atmosphere. You should come in on a Friday -- it's a party! We just want to give people good food and a good feeling."

Our final bites were actually two gulps -- one for each of us -- of a dish called "honeymooners." This combination of reputed aphrodisiacs includes some of my favorite flavors: a raw oyster, a quail egg, a lobe of uni, and a scattering of wasabi-tobiko (flying-fish roe, stained green and flavored with Japanese horseradish). The method for assembling these ingredients differs from chef to chef, but in all versions, the diner is supposed to make a single huge, melty-crunchy mouthful of it. Hugo mixed the ingredients like a cocktail in a wine glass, then drenched them in spicy ponzu sauce. Using chopsticks to get the mixture moving up the glass, we poured the potion into our mouths. The liquid tasted like spiced champagne -- a glorious after-dinner drink that warmed us all the way home.

* * *

Coronado has no shortage of restaurants, but when an "institution" becomes a sushi bar, it's news. The Lizard Lounge is an age-old saloon, dating from the days when lounge lizards in leisure suits roamed the earth. Over the years, the pleasant restaurant attached to it (currently Bistro d'Asia) has undergone numerous changes of ownership, name, and format, but the Lounge has endured as a quintessential Coronado watering hole, drawing a convivial Navy-heavy crowd of regulars. But this lizard can change its color, and a reader named Jade recently e-mailed me to say that the Lounge now includes a good sushi bar. She sounded as if she knew her sushi, and as it turned out, she did.

Friends and I arrived early one weeknight and discovered that the streetside end of the traditional wooden bar had been converted to a short fish counter, where Tim Manley heads the operation. Most of the barstools were already occupied, with something of a blue/red division: Younger folks (under 65) ate nigiri or futo maki at the left (sushi) end, while retirees slurped noodles and Scotch on the right. But the atmosphere is friendly wherever you sit. A lanky blue-eyed lady wearing a watch cap volunteered to move over one stool to give our trio room to sit together. "I've been to almost every sushi bar in the city," she told us, "and I like this one the best. I come here several times a week." I asked what roll she favored. "I always get the hamachi," she said. She was working on her dinner's grand finale, a California-roll variation topped with albacore and lemon slices. "I just wanted one piece of this," she said. "Help me out. Take the rest of it." How could we refuse? Lean white albacore is far from my favorite fish, but this combination was refreshing.

Eighteen or so rolls are listed on the menu, but additional choices are available for the asking -- just tell Tim your desires. You can also order dishes from the restaurant kitchen, the source of both the other-end-of-the-bar's noodles and our own golden, cloudy (and satisfying) miso soup.

Tim grew up in San Diego. "I started out bussing and then waiting tables at a sushi bar and became interested in getting behind the counter," he says. "I've always been sort of artistic -- I love to draw and paint -- and I just loved that creative part of sushi. So I started asking the chefs a lot of questions. Then I apprenticed at Hayama in Mission Valley for a number of years. I worked for a few years at Zao in La Jolla. I've been at Lizard Lounge since the owners added sushi over two years ago. A friend of mine was a waitress here and told me they were looking for somebody."

We began again with uni. The urchin was Grade A -- fresh, sweet, with a pillowy texture -- and this chef, too, was generous. Although the rice was slightly loose (in all the rolls we tried), it was freshly cooked and flavored with a just-right amount of sushi vinegar. Next, we tried nigiri, a warm and savory eel. The sweet brown "eel sauce" was less cloying than the average version.

The Lizard's spicy scallop hand roll was a near-paragon of the form, its spiciness zingy but not painful, balanced by cucumber, avocado, and Japanese mayo (a little bland, once again). These ingredients, along with fresh-tasting scallop pieces, ran all the way through the roll. The mixture seemed almost sweet, like a spicy fish-flavored ice cream cone -- and I mean that in a good way.

Ama ebi were set atop rice dressed with wasabi, their heads stuck into a sweetened wasabi dressing. The heads were too heavily floured for my taste, but the shrimp themselves were distinctly sweet.

Ahi poké (from the sashimi list) offered sinew-free cubes of tuna mixed with seaweed, cucumber, and avocado. But instead of bathing Hawaiian-style in a toasted-sesame oil dressing, the ingredients felt dry under an overabundance of sesame seeds and tobiko roe.

Finally, it was time to check out some party rolls. Nearly all of Lizard Lounge's inside-out rolls are variations on California rolls, with the same center of crab and avocado. Some have coatings of seaweed, avocado, tobiko, or other species of fish. Some have "soy paper" exteriors instead of rice, to please carb-counters. The most creative is a mango-albacore roll, featuring tempura shrimp, avocado, white tuna and ponzu, with mango on top.

The party rolls taste delicious, but given their similarity and size, you only need one per dinner. The plain nigiri rolls, on the other hand, are worth exploring in all their varieties. The ability to make the most of the simplest rolls is typical of Japanese-trained sushi chefs -- and one mark of a good sushi chef from any country.