He identifies himself as the sommelier at the spacious new Johnny’s Half Shell on Capitol Hill, but Denis Sirieys is actually a manager here, though one with prodigious amounts of wine knowledge. Whatever his role, Sirieys proves to be unflappable when our loopy waitress fails to tell him that the two bottles we just ordered for dinner were supposed to be poured anonymously, as part of our spontaneous decision to conduct a blind tableside tasting to see if we can tell an Oregon pinot from a Burgundy.

So even after he has poured the first bottle with the label in full view, Sirieys tells us not to worry—the game’s not over yet. He then trots out a second bottle wrapped in a brown paper bag, bum-style. He does the same with a third, a mystery bottle compliments of the house, presumably for ruining our planned drunken fun. Much later, with our test complete and our egos bruised from our pinot ignorance, Sirieys challenges our buds one last time with a gratis glass of one of his favorite grapes, a young-and-tart black gamay. We proceed to toast Sirieys for his good taste in plying us with free wine.

Only after we pay up do I realize that Sirieys has done what no one, or nothing else, has done during my two previous visits to the new Johnny’s Half Shell: He has made the place seem as cozy as the old location off Dupont Circle. A former manager at La Colline, which occupied this Capitol Hill space prior to Johnny’s move, Sirieys has managed to collapse the vast landscape of wood and tile into a scene as intimate as a backroom deal. He does it not with free vino—though that doesn’t hurt—but with his ability break free from the strict, circumscribed roles of staff and diner. He becomes part of our party. He even drinks with us. The new Johnny’s could use more of Sirieys.

Chef Ann Cashion and namesake John Fulchino have made no bones about their desire for more space. Their previous 1,800-square-foot location on P Street NW could seat only 60; their new 10,000-square-foot space, which includes a patio, has room for 300 butts, not including the outdoor piano player’s. The fivefold increase in potential patrons, of course, comes with its own multiple headaches behind the scenes: adding and training new staff, ensuring suppliers (the vast majority of them organic) can meet the extra demand, and pushing a kitchen to maintain quality and consistency on a much larger scale.

The owners have worked hard to address all of these issues and more; they have even tried to remake La Colline into the image of the old Johnny’s. But space and location are unruly children. So while the new space features many of the same elements as the old—the marble bar, the seafood-themed art, the great expanses of wood, the tile floors—the lofty, L-shaped restaurant exudes the kind of gavel-pounding authority more associated with its domed next-door neighbor, whose denizens dine here in all their power-tie and pearl-necklace glory. Even the wait staff’s lab-coat attire, a carry-over from P Street, takes on a more clinical feel in this space.

The restaurant’s newfound air of authority places the burden on the kitchen to keep the place grounded—to help make sure the influx of muckety-mucks don’t completely strip Johnny’s of its old charm and turn it into the next Old Ebbitt Grill. Cashion, despite the challenges of the expanded room, mostly holds up her end of the bargain, still turning out the honest, deceptively simple seafood that draws on both the Atlantic and the Gulf for inspiration. She has added only a few new items to the menu, including her latest creation, plump pieces of white chicken in a spicy étouffée sauce, the whole of which regrettably suffers from an excess of flour and breading.

Her old standbys continue to do most of the heavy lifting: a pair of Maryland crab cakes, fried or broiled, which let the sweet meat do the talking; a selection of lunchtime po’ boys (including one stuffed with her otherworldly fried oysters, at once crispy and tender); a razor-thin fillet of rainbow trout, grilled to perfection and drizzled with a delicate dill-butter sauce with a hint of lemon; and fritto misto, a heaping plate of expertly fried finger food from the sea (save for the overly breaded and greasy green tomatoes).

The expanded kitchen sometimes shows signs of being asleep at the grill—or oven or sauté station. A Baltimore hot dog arrives completely blackened on one side and tomato-red on the other, its bun likewise burned on the rack. A filet of dry-aged beef, tasting of pepper and black char, has clearly been seared too long on the hot side of the grill, and the royal trumpet mushrooms on an otherwise sweet and flaky Alaskan halibut have been oven-roasted to the point of dehydration. These missteps from Cashion’s usually meticulous kitchen serve as reminders that expansionist dreams often have their harsh realities—and help us remember why chefs such as Johnny Monis at Komi and Jeff Black at Black’s Bar and Kitchen have cut back on the number of seats in their dining rooms. Cashion and Fulchino really want to maintain the cozy seaside spirit of their old place, but that Johnny’s is gone forever, swallowed whole by this new, glistening whale.

Johnny’s Half Shell, 400 N. Capitol St. NW, (202) 737-0400.—Tim Carman

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