Watching a hospitality group wander beyond its comfort zone can be exhilarating. Locals may know Big Night Entertainment Group from its glitzy Foxwoods nightclubs and Boston hot spots like Red Lantern and Empire. With their over-the-top decor, high-decibel DJs and hookup-ready crowds, the scene at those places takes precedence over food. Explorateur, Big Night’s newest venture, occupies a stunning room in Boston’s old Grand Masonic Lodge, embodying a lively but dignified cafe-cum-brasserie that is more Belle Epoque than va-va-voom Vegas. With its menu of French, Italian and American staples, it’s hard not to be reminded of Eastern Standard Kitchen & Drinks, a pretty high bar to aspire to. So how well-advised is this bold venture?

Cocktails are a promising first point of comparison, served by a better-trained bartending staff than is typical for Big Night. Credit bar manager Gina Goyette, whose experience managing wine and beverage programs in New York shines through. Before you order the Exceptionally Long Last Word ($19), you pray the bartender will measure and mix its costly V.E.P. Chartreuse component carefully, and sigh in relief when she does. An exactingly crafted half-and-half martini ($12) is equally perfect and delicious. When it comes to wine, the French-heavy list is easy to navigate and fairly priced, from the modest house half-liter carafes ($21) to 20 wines by-the-glass ($9-$25, most under $13) and a list of 100 bottles (most under $75). The beer list (six drafts, 11 packaged options, $5-$10) is just interesting enough, neither too geeky nor lowbrow.

The dinner menu by chefs Michael Morway and Jacob Mendros is more of an adventure. Salads range from a solid frisée aux lardon ($13) with soft-boiled egg, copious chewy lardons and judicious vinaigrette to a salad niçoise ($15) that impresses in most of its details (olives, haricot vert, confit potatoes) but is marred by flavorless slices of mediocre seared tuna. The Explorateur salad ($14), an assortment of kale and marinated vegetables, is so underdressed that one wonders if the kitchen just forgot a step: risibly bad.

Salmon crudo ($15) is a currently trendy dish that restaurants should shun if they’re not willing to charge for pristine-quality fish. Explorateur isn’t, and like the niçoise’s tuna, the result is mushy and dull. Onion soup gratiné ($10) does a better job of hitting its canonical bistro marks with good beef stock, some sherry sweetness and the gooey charm of a gruyère-laden crouton. One of the nicest surprises of the night turns up in this small plates section, a crisp, thin-crusted veggie flatbread ($15) with sweet-potato puree that delivers a saucy texture and sweetness normally supplied by tomatoes, and topped with lovely roasted aromatics, mushrooms and summer squashes: a smash.

Entrees also careen between hits and misses. The New York strip loin on the steak frites ($25) has an oddly soft texture, as though it had been mechanically tenderized; more important, it is seriously underseasoned, with the head-scratching accompaniment of a few mesclun greens (did they run out of watercress?) but some good egg-salady gribiche. About the best one can say for the chicken paillard ($18) is that it’s big. The pair of barely-pounded breasts with some decently crispy skin is filling but somewhat dry and bland, again lacking much-needed salt. Halibut ($18) can’t be blamed for being a mild fish to begin with, but its treatment doesn’t meet the menu description: The brown butter isn’t browned, and the promised capers are entirely missing, with forgettable results. Then along comes spaghetti ($16) with cherry tomatoes, garlic, olive oil and parsley, which turns out to be simple yet sensational, with the welcome, unexpected texture of housemade pasta. Whole roasted chicken for two ($45) is likewise a home run, beautifully browned all over, juicy and crisp-skinned, with an exquisite madeira jus underneath, alongside a fistful of homey, nicely browned gnudi, fritters of ricotta, egg and cheese.

Pastry chef Morgan Gray plates some crowd-pleasing standards, like a very sweet honey lavender crème brûlée ($10) with fresh berries and excellent lemon sablé cookies as well as a not-salty salted chocolate pots de crême ($10) with more fresh berries and good whipped cream. Most impressive is a terrific brown butter soufflé for two ($16) with a coarse dice of roasted pineapple on the side and a pitcher of vanilla crème anglaise to drizzle into a hole you’ve poked to access its airy, steamy interior.

Despite the somewhat disjointed interior—with its breakfast-and-lunch coffee counter, pastry cases and long communal tables up front—the space overall is dramatic and gorgeous, with soaring ceilings, tall windows overlooking the Common, and classic accents of bronze, subway tiles and marble. Those hard surfaces make for a painfully noisy room at peak periods. Service also has its punishing edges, with uniformly solid technical but uneven hospitality chops behind the bar, servers that drop entrees without bussing finished apps first, and one unfortunate, unbidden decision to dump a whole pitcher of sauce on our soufflé (let the customer do that to taste, please). Partiers in search of justly-famed Big Night style and sizzle will surely find it here, but until Explorateur’s kitchen reaches a more consistent level, one might not want to essay dinner here without a map. ◆

MC’s Picks
Frisée aux lardon
Onion soup gratiné
Roasted veggie flatbread
Spaghetti with tomatoes
Whole roasted chicken
Brown butter soufflé

Explorateur, 186 Tremont St., Boston (617-466-6600) explorateur.com; Hours: Breakfast, 7 am—3 pm; Lunch, 11:30 am—3 pm; Dinner, Sun.-Wed., 5-10 pm (bar till midnight), Thu.-Sat., 5-11 pm (bar till 1 am) Liquor: Full; Reservations: Yes; Parking: Metered street spaces, nearby garages and lots