Consider it a treasure hunt. You may need a secret map to find Farmhaus, but there are great culinary riches at the end of the quest.

Chef Kevin Willmann developed a loyal following over the past several years at Erato in Edwardsville, where he augmented a fan base from the immediate area with a significant number of diners who trekked from the Missouri side. That gave him a ready-made audience as he gradually opened Farmhaus in south St. Louis, teasing them with a limited lunch menu before offering weekend dinners and then slowly expanding his evening service.

His chosen space on Ivanhoe Avenue already had housed two relatively short-lived restaurants, plus one whose lifespan seemed to have been measured in days. That led some to speculate that the location was too obscure to support a fine-dining restaurant. And, just in time for his opening, the location went from off the beaten path to down the rabbit hole, owing to construction on the nearby Arsenal Street bridge.

Willmann's finished dishes also follow complicated roadmaps, but he and his kitchen staff invariably take diners to some very interesting destinations.

Take, for example, his charcuterie plate ($14), which started with two discs of torchon, a labor-intensive delicacy in which foie gras is marinated and poached, then tightly bound into a tube shape and sliced into discs. In Willmann's version, the smooth and rich yet subtle liver flavor was wrapped up with chunks of smoked chicken, with the traditional truffle addition provided by a truffle mustard. The tang of the mustard played off the chicken without overwhelming the foie.

The next item on the plate was a piece of lavash covered with a quilt of thin slices of housemade small-gauge saucisson sec, a cured meat with a dense, pure pork flavor. Also included was a cooked pork sausage that looked like a large breakfast link, but again had a wonderful pure flavor and was complemented by Funks Grove Maple Sirup, a sweet idiosyncrasy from a century-old producer about 150 miles up Route 66 in Illinois.

The local angle is clearly important to Willmann, but he's not a purist, especially because he specialized in seafood previously in his career. Still, the fish preparations at Farmhaus always contain some element to tie them back to this area. Escolar ($15) — a 4- or 5-ounce rectangular fillet of firm, rich fish — was poached in butter, dill and the off-dry local wine Traminette. The topping of grilled blue prawns was served head-on, and the shrimp had their own unexpected buttery flavor, with the whole thing anchored to the earthy side by a bed of black trumpet mushrooms.

Except for two or three nightly entree specials at the end, the menu is presented as small plates, with a meal for two comprising five or six of them. Nothing that we sampled lent itself to brief description, but in the interest of illustrating the scope of the menu, I'll try: "Nachos" ($7) were sweet potato chips, tangy blue cheese, thick-dice smoked bacon and red-pepper flavors that played together perfectly. Long, flat pappardelle ($14) was an ode to unusual local spring greens — tiny sorrel, tatsoi and baby bok choy, plus fiddlehead ferns — recited with the trendy accents of mellow, almost sweet black garlic and pearl onions cooked sous-vide.

The one entree-sized portion we tried, Hudson Valley duck breast ($22), included eight moderately plump slices made special by a crispy rendering of the fat along their edges.

Even desserts were meticulously plotted out, such as the sweet potato pie, served with a mini-scoop of sweet potato sorbet and raised to another level by candied sage, which provided a mintlike flavor, but with a sharp, pronounced edge.

The farmhouse motif in the decor is vague, established mainly by brown paper on white linen tablecloths and some vintage wood soda crates partially populated by empty bottles, along with a couple of cute mutts who occupy the backyard, yapping occasionally when they're not peering in the door.

Our servers knew the intricacies of every dish (as well as the quirks of the wine list, such as a shiraz with sugar added), but they were only as attentive as staffing allowed, slightly overworked when the restaurant hit capacity on a weekend. Pacing was also irregular, although that could be attributed to the kitchen coming up to speed on the relative complexity of the menu items, which change daily.

It's sometimes said that getting there is half the fun, but in the case of Farmhaus, right now getting there is almost no fun at all. Once you arrive, though, buckle up for a real adventure.

žœ 3257 Ivanhoe Avenue • 314-647-3800 • Menu: About 14 small plates and a couple of entree dishes, with lots of local provision but also several seafood selections • Smoking: No • Hours: Lunch, 11 a.m.-2 p.m. Monday-Friday; dinner, 5:30-10 p.m. Wednesday-Thursday, 5:30-11 p.m. Friday-Saturday