Robyn Baitcher Wechsler’s Currywurst & Bratwurst, 120 First Avenue.

It was the second-to-last day of Oktoberfest at Wechsler’s, a midget wursthaus — more like a wurstkiosk — at 120 First Avenue, between Seventh Street and St. Marks Place. Andre Wechsler, the eponymous owner, had his barman/waiter/busboy pour a draft of Schneider Weisse beer and another of Radeberger Pilsener. Each arrived in a glass from its own brewery. It would be an insult to Andre to say the foam on each was just so — of course it was. Still, my friend Birte Kleemann, who ran an art gallery in Berlin before becoming director of The Pace Gallery in Chelsea, had a probing question: “Are these German strength, or American?” The typical alcohol level of German beer, Birte explained to me, was 5.45 percent, slightly above the strength of the dishwater served in this country. Andre solemnly averred that the provenance of both was pure German. “Actually,” he added, “the Schneider Weisse is 6.2 percent—special for Oktoberfest.”

Germany is a serious country; and Wechsler’s is a serious little restaurant. Of course anyone can enjoy beer and sausages without a tutor, but it’s helpful to bring one along for the same reason it’s good to go to a ballgame with a fan — you’ll appreciate the nuance. Had I not brought Birte with me, I would not have noticed, for example, that Andre serves his bratwurst in a narrow cardboard tray with a little tab at the end, which the diner tears off to use as a handle in order to pick up the brat and dunk it in the bucket of mustard. I would not have known how to eat the weisswurst either. “There are two ways,” Birte explained. “I’ll show you the way my Mom taught me.” And she promptly sliced the soft, rubbery wurst down the middle, splayed it open and peeled off the skin backing — a sausage filet.

Two or three generations ago, any New Yorker who cared about his stomach would have been familiar with German cuisine; now you can barely find a proper delicatessen. The loss is ours. After spending an hour on a bar stool between Birte and Andre, I understood that even this casual, sidewalk cuisine harbors deep secrets and weighty calculations. One of Wechsler’s side dishes is kale sauteed in white wine with bacon. When it arrived, Birte frowned and said diplomatically, “This is very different from the way I know it.” (I thought it was great.) “We weren’t able to find the right sausage,” Andre admitted dolefully. Apparently, kale is supposed to — there were quite a few supposed to’s in the conversation — come with double-smoked sausage. Andre would not substitute an inferior product, any more than he would serve the suffocatingly spicy mustard from the Ukrainian store nearby. With German mustard, he said, “the taste goes away in a few seconds.” And it was true.

Robyn Baitcher Inside Wechsler’s, where the foam on each glass of beer is just so.

The sausages at Wechsler’s are just outstanding — even Birte thought so. One of the house specialties is currywurst, a Berlin delicacy in which a sausage made of veal and pork is sliced into thick rounds and covered with a sweet, curry-infused tomato sauce, and served over a bed of french fries. Currywurst is typically consumed to round off a long night of eating and drinking, which appears to be a fairly common German experience. “You never get a hangover if you eat it,” Birte said, since the curry acts as a digestive. I gather that this is an important attribute. Birte also noted that “the great advantage” of the Rissdorf Kölsch beer Andre later poured for us is that “you can drink ten of them without getting drunk.”

While Birte is an exceptionally enthusiastic and passionate person for someone who sells difficult art for a living, Andre is perhaps unusually reserved for a man who sells beer and sausages. Andre was an accountant and then a banker; his firm moved him to New York, and he and his wife decided to stay. He opened for business in February 2009. Andre is a big, almost hulking man with a light, golden stubble, but he doesn’t take up much space. I’ve often seen him quietly reading a paper at the counter.

Andre says that the tables in the back seat 18, which I find hard to believe, or unpleasant to contemplate; he is hoping to open out a wall and put a beer garden in the back, and thus add another twenty or so seats. Like many restaurants in the neighborhood, Wechsler’s is often empty during the day, and often packed at night. The dinner customers are not so discriminating; if you come at lunch, Andre will be happy to tell you what you’re eating.

Wechsler’s Currywurst & Bratwurst, 120 First Avenue.