Your mission: Find Mesa’s front door

I heard about it from an O.C. friend: a new restaurant and lounge just opened in Costa Mesa. It’s one of those clandestine deals, he told me. No listed phone number, no sign, no address out front. A friend of a friend who knows the sommelier told him about it, and despite appearances (or lack of them), this was no hipster martini lounge, but a real restaurant headed by the former chef de cuisine at AOC.

He graciously slipped me what passes for the restaurant’s business card: a 714 phone number printed crookedly on recycled brown paper. No address. No details. Not even the name. It’s called Mesa, by the way. Google it and nothing comes up -- no reviews, no website, nothing.

Mesa is meant to be Orange County’s Hyde or Green Door, those L.A. hot spots where everything about it is kept secret to keep the hoi polloi out and the cool kids in. Mesa’s owners, it turns out, have experience creating buzz: They also own Firefly in Studio City. With Mesa they have the Hollywood-style restaurant/lounge thing down.

I rounded up some friends and gave the number a call. After all the intrigue, you’d think it would be hard to book dinner, but not really. At least not at 8 or 8:30 on a weeknight.

My friend had told me that it’s next to the Camp, a so-called alternative mall not far from South Coast Plaza. Look for a big white bunker-like building, he said. Well, we drove in one entrance to the Camp and out the other, came around a corner and were about to head back when I spotted the valet station and two blonds stepping out of a BMW, both in shiny black boots with 4-inch heels.

This must be the place.

We followed them down a covered walkway to a drafty entrance, controlled by three hostesses wrapped in winter coats. OK, our name is down, we’re in. And we can’t help feeling smug about it. I don’t know how everybody else found out about Mesa -- Facebook or friends of friends of friends, like me -- but they’re here.

In fact, the lounge is thronged: Women commandeer the long communal table, dangling long legs from the high stools, sipping cocktails and getting silly and loud. Smokers light up -- a retractable roof makes it OK -- between bites of frites or shrimp. Cellphone cameras snap pix. Laughter ricochets off the walls. Fortunately, the roar is mostly on that side of the room.

Head to the vast dining room and grab one of the quiet leather booths, where you can survey the entire room as the scene unfolds. I can’t think of another place in Orange County that has such an edgy look, eclectic crowd and lusty food. Everybody loves a secret. And Mesa is a good one. Chef John Sadao’s menu is inventive and delicious, and in case you’re wondering, yes, it’s very much like what you’d get at AOC, which is a good thing.

Close your eyes and point at the one-page menu of small and large plates and you almost can’t go wrong. Order a platter of artisanal salami and you get three Fra’ Mani selections -- toscano, nostrano and salametto, all as authentic as you can find in this country.

Golden fritters

BUT the bread is slow in coming, and when it finally does arrive, it’s not enough to go around. Brandade fritters, each more than 2 inches across, are beautiful, crisp and golden, made of finely shredded salt cod mixed with potatoes and accompanied by a subtle Meyer lemon aioli. Fried baby artichokes are a must. This is more of a classic fritto misto, a mixed fry of the tender artichokes with sliced fennel and chickpeas with lemon squeezed over. I could eat an entire order myself.

Order a wine, though, and your waiter may ask, “Two?” -- assuming that you’re ordering glasses. That would seem to imply not many bottles are being ordered, but more cocktails and glasses of wine. Too bad, because there are some nice bottles, many less than $50, on the list put together by sommelier Andrew Merritt.

There are even a few Vouvray secs -- dry Chenin Blancs from the Loire Valley and a couple of premier cru Chablis that drink well with the fried dishes. Reds include Pinots from the Hitching Post in Santa Barbara County, a terrific Anjou Rouge, also from the Loire Valley, and some pricey Cabernets from Napa Valley.

Any of them would be swell with the braised pork belly, a single succulent slab served over soft polenta with a small fennel salad. Hey, that’s a small plate on this menu. And for vegetarians, there’s winter squash roasted to concentrate its flavor and served with dandelion greens and walnuts drizzled with saba, or grape must.

Of course, the singles at the bar are merrily ordering up Mesa frites, golden fries showered with rosemary, sage, parsley and thyme. Another item to share is the wood-oven roasted flat bread. Long and skinny, it’s cut into pieces and piled high with diced tomato, cauliflower, and olives tossed in a bagna cauda. That’s a hot bath of garlic, anchovies, butter and olive oil. Rich, eh? And a nice variation on the pizza theme.

While we’re eating, managers in rumpled suits prowl the outlines of the bar, checking up on service, looking for any problems. Over on the lounge side, hardly anybody is in twos or threes. It’s mostly bigger groups sprawled around the coffee tables, ordering up organic margaritas and blood orange Manhattans, trilling into cellphones and meeting up with friends.

The restrooms are unisex: men’s stalls on one side, women’s on the other, everyone meets in the middle over the sinks. At the very back, a woman I’d noticed up front has set up an easel and canvas and is busy painting something abstract. In the restroom. Wild! But I did say this place is artsy, didn’t I? What’s next? A performance artist on a trapeze?

Meanwhile, back at the table, the large plates, all $20 or less, are arriving. I’m happy with the wood-oven roasted prawns with black-eyed peas. It’s a rustic, full-flavored dish that you’d never expect at such a trendy venue.

A lavish burger

THE Mesa burger is lavished with caramelized onions and nutty Gruyere cheese, which I think makes a better burger than the more popular blue. It comes, of course, with an order of Mesa frites big enough to share.

Steak lovers can settle in with a Niman Ranch hanger steak. Just ask for it rarer than you really want it. The kitchen tends to overcook (you might also ask for that Port wine sauce on the side, because it’s a bit strong for the beef). New Zealand lamb chops make a fine supper too.

After, get the selection of four cheeses, which may include an aged pecorino, a goat’s cheese and a blue. The dessert list constantly changes, offering homey nostalgic sweets such as gingerbread with tangerine curd, baked Pink Lady apples with butter cookies or chocolate sorbet with berries. Ice creams and sorbets are house made and may be the best bet after indulging in so many small plates.

Sadao’s cooking at AOC was terrific, but at Mesa, maybe because he doesn’t have such a seasoned team or such an exacting mentor as Suzanne Goin, the execution is iffier. One night everything can be spot on, another night inconsistent.

Even so, the food is so much better and more interesting than at other places in the neighborhood, it deserves to be added to every O.C. food lover’s address book. Some won’t like the noise level; others won’t like the casual menu or the service. But for most, Mesa will be a definite keeper.

So here is the address. And the phone number. I’d like to show it to you too, but sorry, this place wasn’t letting a news photographer through the door.

virbila@latimes.com

Mesa

Rating: **

Location: 725 Baker St., Costa Mesa; (714) 557-6700.

Ambience: Edgy contemporary restaurant and lounge in a bunker-like building with a huge central bar, lounge with retractable roof and dining area with leather booths. The crowd is artsy and eclectic, the energy high-pitched. The food is rustic but sophisticated, from a former chef de cuisine at AOC. The calling card has simply the phone number, no address.

Service: Casual but friendly.

Price: Small plates, $5 to $12; large plates, $14 to $20; desserts, $7 to $9.

Best dishes: Artisanal salami, fried baby artichokes with fennel and chickpeas, brandade fritters, roasted winter squash with walnuts and dandelion greens, braised pork belly with soft polenta, Mesa frites, wood-oven baked flat bread, Mesa burger.

Wine list: Wide-ranging and eclectic, with a number of good choices less than $50. Corkage, $20.

Best table: A corner booth.

Details: Open for dinner 6 to 11 p.m. Tuesday and Wednesday and 6 p.m. to midnight Thursday to Saturday. Bar and lounge stay open until 2 a.m. Full bar. Valet parking, $4.50.

Rating is based on food, service and ambience, with price taken into account in relation to quality. ****: Outstanding on every level. ***: Excellent. **: Very good. *: Good. No star: Poor to satisfactory.