Every Thursday, a little randomness arrives at Benkay. It comes in the form of a shipment to the restaurant’s new home on Middle Street in Portland – in boxes that are cold to the touch, imposingly heavy and branded with vendors’ logos from perhaps the world’s most famous fish market: Tsukiji, in Tokyo. And until chef/owner Seiji Ando slits them open, their contents are a complete mystery.

“Once a week, it comes. Different special fish, and we don’t know what’s inside,” Ando said. “We haven’t had anything come yet that we don’t know what to do with, but we have no choice in the assortment. It’s kind of interesting to us and interesting for the customers.”

Tuna tataki

BENKAY

RATING: ***

WHERE: 16 Middle St., Portland. 773-5555, sushiman.com

SERVING: 11:30 a.m. to 2 p.m. and 5 to about 9 p.m. Monday to Friday, 11:30 a.m. to about 9 p.m. Saturday and Sunday

PRICE RANGE: Appetizers and individual rolls $2 to $16, entrees and sushi meals $16 to $55

NOISE LEVEL: Parent-teacher conference

VEGETARIAN: Some dishes

GLUTEN-FREE: Many dishes

RESERVATIONS: Yes

BAR: Beer, wine and cocktails

WHEELCHAIR ACCESS: Yes

BOTTOM LINE: To many Portlanders, the name Benkay is synonymous with sushi. Open for the better part of 20 years in a tiny, nondescript storefront on lower India Street, the restaurant relocated in January to posh new digs on Middle Street. For chef/owner Seiji Ando, the move is an exciting one that offers him a chance to seat more diners and to prepare a weekly special-importation menu, thanks to a mystery shipment of fish that arrives every Thursday from Japan. The sushi he prepares from it are wonderful, especially delicate medai and gently tangy shima-aji (horse mackerel). His botan ebi, a sweet jumbo shrimp, served with its deep-fried (and edible) head may not come in that same shipment, but it is worth ordering, as are the savory chawanmushi custard and the seared tuna tataki. The regular sushi is mostly decent, if unremarkable. Your best bet is to visit on a Thursday or Friday, before the special fish disappears. Then grab a green tea ice cream sandwich ($5), but be prepared to take it to-go in case the unpredictable closing hours force you out earlier than you expect.

Ratings follow this scale and take into consideration food, atmosphere, service, value and type of restaurant (a casual bistro will be judged as a casual bistro, an expensive upscale restaurant as such):

* Poor ** Fair *** Good **** Excellent ***** Extraordinary

The Maine Sunday Telegram visits each restaurant once; if the first meal was unsatisfactory, the reviewer returns for a second. The reviewer makes every attempt to dine anonymously and never accepts free food or drink.

Diners do seem to respond well to the premium fish selection, which Ando lists by hand on a chalkboard behind the golden-hued sushi bar. One by one, the names of fish such as light, clean-tasting medai (butterfish, $4) and whisperingly tangy, funky kohada (gizzard shad, $4) are appended with a somber label: “OUT.” By the time dinner ends on Thursday, half of the Tsukiji selection is gone. By Sunday night, it is sold out.

Fortunately, not all Benkay’s specials come from Tsukiji. Ando makes a point to use local uni (sea urchin), lobster and scallops wherever possible, as well as other North American fish, like akagai (surf clam) from the North Atlantic and tuna fished off the coast of North Carolina. Plenty of other seafood options arrive from Japan, even if they are not packaged and shipped overnight from Tsukiji Market.

One, sweet botan ebi (jumbo shrimp, $4), comes from the frigid waters of northern Japan. Ando prepares it nigiri-style, served tail-on and raw, draped languidly over a mound of vinegar-sprinkled sushi rice and accompanied by the deep-fried, salted head, which is eaten whole: shell, antennae and all. Mineral and violently crunchy, it is perhaps the best single item on the menu, even though it is a special.

The barely seared tuna tataki with wasabi olive oil and togarashi shichi-mi pepper ($12) comes a close second. Better still, it is on the expansive regular menu, along with another winner, chawanmushi, a steamed egg custard made with dashi, or Japanese fish stock ($5). While the chewy scallops indicate it is cooked a bit too long, the overall dish is a delight – warm and homey, with a comforting savory charm that leaves you scouring the bottom of the bowl.

On a recent Thursday night visit, I found other items from the regular menu to be more hit-or-miss, like the mango-vodka-based, perplexingly named Silk Pie martini ($8) that tasted like something you might drink from a juice box. Or the gokudo maki ($6), a mackerel roll where fish is bundled tightly along with pickled ginger and a spicy Kewpie mayonnaise. An invention of Masahiro Matsuyama, the owner of Yosaku, who worked at Benkay before starting his own restaurant, the maki delivered a punch of ginger to counterbalance the fishiness of mackerel, but almost no fire from the sauce.

Another wobble came in the form of a tempura appetizer ($8) made up of squid rings (no tentacles), thick slices of zucchini, sweet potato and green pepper, all dredged in a fine wheat-flour batter and deep-fried. Perhaps too quickly, though. Most of the vegetables were undercooked and unpleasantly tough. “I know tempura is supposed to be crunchy,” my dinner guest said, holding up a nearly raw yam between his chopsticks. “But not on the inside!”

The “sushi regular” set meal ($26) was just as underwhelming, with components that might have come from a different, less accomplished restaurant. Like bland hamachi (yellowtail), dry ika (squid), and California rolls that reminded me of supermarket sushi. The best part of the platter was a melon-sweet orange tobiko (flying fish roe) gunkan roll. Clad in a layer of nori, it gets its name because it resembles a battleship, albeit one enrobed in thousands of miniature pearls that pop like bubble wrap when you bite down.

Some dishes are probably not for everyone, like keenly fishy-tasting wakasagi (smelts, $5) simmered in sake, ginger, soy sauce and mirin until they are shiny with a savory, caramelized glaze. I adored them; my dinner guest did not.

We both agreed on the negi (green onion) hamachi maki ($6), though. Made by rolling yellowtail with scallions sliced as finely as hair, they were a little too skimpy with the negi and wound up tasting like plain hamachi sushi. Decent enough, but without much of a sulfurous spark.

Before I left, I wanted to sample another few maki, but our server very gently dissuaded us, pointing out that she had already turned away two parties who came in to be seated.

A suit of samurai armor in a display case greets patrons at the entrance of Benkay at its new location, 16 Middle St. in Portland.

What time, I wondered aloud, does Benkay close? It’s not listed on the website, the menu or the door. “We don’t really have a time when we stop serving,” she replied. “When we don’t have customers, we just close the doors.” As if on cue, a young couple walked in and were swiftly rebuffed.

Seconds later, the kitchen crew emerged from the back and began mopping the dining room with an eye-watering, floral-scented cleanser. Evidently, at 8:54 p.m., it was time for the remaining three tables to leave, whether we wanted to or not.

When I asked Ando about the restaurant’s hours, he echoed what our server had said. “We usually close between nine and ten o’clock,” he said. “But it depends on how many customers come. We actually prefer when people make a reservation.” That’s good advice, especially on a Thursday, when the special Tsukiji menu debuts – as much of a mystery as Benkay’s closing time.

Andrew Ross has written about food in the United Kingdom and in New York, where he co-founded NYCnosh, a food website. He and his work have been featured on Martha Stewart Living Radio and in The New York Times. Contact him at:

andrewross.maine@gmail.com

Twitter: AndrewRossME