Even in a city full of creative riffs on traditional ramen recipes, Mu Ramen’s beef-based namesake is unlike any other, suffused with the great New York flavors of half-sour pickles and corned brisket. Experiments like this might not be so successful if it weren’t for chef Joshua Smookler’s intense focus on quality over quantity (the restaurant seats about half as many people as it could actually fit, in an effort to ease the kitchen’s burden). Other options are just as impressive: There’s a regal duck shoyu, clean like consommé, and a killer tonkotsu “2.0,” Smookler’s take on the potent, heady broth made of pork bones and meat boiled for hours. The chef refines it just enough, by skimming off the fat, allowing its concentrated porkiness to come through more clearly. Beyond ramen, there’s a menu of similarly tinkered-with appetizers: okonomiyaki made with Western-style pancakes and smoked trout, sautéed clams in spicy dipping sauce, and a much touted but ultimately disappointing tebasaki gyoza or deep-fried chicken wing that’s stuffed with foie gras.