If you stood at the northeast corner of the South End in 2012, you’d have beheld a foreboding industrial wasteland centered on the abandoned headquarters of The Boston Herald, recently fled in favor of the newly bustling Seaport; you wouldn’t want to linger. Leap forward four years, and that once-benighted stretch is now home to Ink Block, a massive complex of gleamingly modern luxury condos, apartments, retail and restaurants. Just as Barbara Lynch’s BL Gruppo once nudged gentrification along in other corners of the South End with high-end spots like B&G Oysters, a group of top talents from her restaurants have banded together to open Bar Mezzana, a swank, modern Italian restaurant specializing in seafood raw and cooked.

Chef Colin Lynch (ex-Menton) showcases his well-honed talents with a roster of crudo combining impeccably fresh, precisely chilled seafood, the delicate knifework of Japanese sashimi chefs, Mediterranean flavors of exquisite olive oil, citrus and vinegar acids, and a gardenful of daintily applied herbal, vegetal and fruity accents. For instance, wahoo ($12), white, slightly fatty and mild, is gently combined with slices of cucumber, a whiff of chili and nutty sesame seeds. Pink, firm, sweet-fleshed kingfish ($12) gets a shower of crisp, tart green apple strips and pungent perilla leaves. Salmon ($12), cut into large chunks that show off its gorgeous marbling, is dotted with a piquant green-chili salsa verde, focusing the attention almost entirely on its luscious texture. Firm, assertive mackerel ($10) get more aggressive complements of radish and ginger vinaigrette. Langoustine ($29) gets the soigné raiment befitting a tiny, perfect little lobster: a beady-eyed head poking out of a mound of crushed ice between two tails topped with luxurious dollops of black caviar, just touched with faint accents of pink peppercorn and lime. Each of these few pricey bites is a heady high-wire act, a marvel of balance in textures, temperature and flavors.

All that expensive delicacy can use the robust, modest counterweight offered by crostini, like the seaside-breakfast combination of radish, butter and white anchovy ($10), or the cocktail-hour canapé comfort of chicken liver topped with thick bacon and balsamic-glazed onion ($8). Heads will turn at the bone marrow crostino ($8), a Flintstonesque mammoth loaded with barely cooked marrow, complemented with the bright, sweet fruitiness of Castelvetrano olive pesto. Generous appetizers center on salads with brilliant produce, like a popping-fresh pea salad ($12) with a few shavings of ricotta salata, and an astonishing (for July) tomato salad ($14) of great local cherry tomatoes, creamy dollops of stracciatella and crisp cucumber and nectarine. Grilled octopus ($16) offers a meatier salad, abundant pole beans and potatoes adding heft to just-chewy, barely charred octopus slices.

Pastas come in appropriately modest portions and wisely let a few key flavors speak. Spaghetti with crab, sea urchin and chili ($22) highlights its rich crabmeat and delicately briny uni, while sweetbread cappellacci ($18) ably counterweight their puddingish, vaguely livery filling with syrupy aged balsamic and crunchy leaves of fried sage. Spaghetti cacio e pepe ($17) doesn’t hit that elusive Roman ideal of sticking-out-all-over-the-plate underdoneness, but packs the punch of great salty romano. The stunning paccheri ($20) with lobster in a thin tomato sauce based on superb lobster stock may contain a stick of butter: It’s like a Connecticut-style lobster roll with pasta subbing for bread. Entrees include an eminently simple, barely crisped, perfectly cooked thick fillet of fluke ($24) served with an herby aioli, and fried rabbit ($24) with chili mayo and lemon to pierce the savory load of a thick batter coating and a smashing fry job. Desserts can feel like an afterthought, though mild gelati and sorbetti ($3) are pleasant enough.

Reflecting beverage director Ryan Lotz’s experience at No. 9, Mezzana brings what is now the craft cocktail program to beat in the South End, with a battery of exactingly made specialty cocktails (all $11) like the refreshing, surprisingly funky Italian 75 of grappa, limoncello, chestnut honey and sparkling wine, and the tropical fruitiness of the ‘I‘ iwi Bird ($11) of spiced gin, Aperol, passionfruit and lime. It’s about time the neighborhood had an accomplished, well-trained bar staff that knows its way equally around raw-egg cocktails and attentive food service. The wine list is nicely versatile, with a mostly Italian by-the-glass list ($9-$16) and a bottle list that mines familiar Old World locales, throws in a few exotic sources and is helpfully organized by easily recognizable varietal characteristics (e.g., “sorta like pinot grigio”). The 70 bottles ($40-$200) run mostly under $60 in white and pink, mostly under $90 in red. GM Heather Lynch (ex-Sportello) has done a worthy job keeping her front-of-house staff as literate on this score as they are in helping diners navigate the finer points of crudo. The dining room is a marvel: soaring ceilings and windows, white subway tile and ceiling beams, seaside tones of blond woods and cerulean fabrics, fluffy-cloud chandeliers high overhead. With 86 seats in the dining room and 38 in the bar, plus a wide-open kitchen in the center, the room is lively without crossing the painful-noise threshold. The 34-seat patio will be more attractive when the neighborhood becomes less of a construction zone.

In the end, that time traveler from 2012 might gawk at Bar Mezzana and its suddenly swank South End environs. Then again, a bunch of seasoned Gruppo veterans going out on their own, doing a glamorous rendition of a beloved European cuisine, lacquering it with highly polished service and a top-shelf cocktail and wine program, and charging prices appropriate to the neighborhood’s new vibe? Maybe we should have seen that coming.

• MC’s Picks                  
• -Wahoo crudo
• -Kingfish crudo
• -Langoustine crudo
• -Bone marrow crostino
• -Pea salad
• -Tomato salad
• -Crab and sea urchin spaghetti
• -Lobster paccheri
• -Fried rabbit

Hours: Mon.-Wed., 5-10 pm, Thu.-Sat., 5-11 pm, Sun., 10:30 am-2 pm, 5-10 pm; bar till 1 am daily Reservations: Yes Parking: Valet, limited street spaces Liquor: Full bar

Bar Mezzana 360 Harrison Ave., Boston (617-530-1770) barmezzana.com