As everyone knows, it’s a whole lot easier to open a full-fledged restaurant in this town than it is to operate a pushcart in the park. At least that’s what Mario Batali once told the Underground Gourmet about his GelOtto gelato-mobile. After a 2004 debut and sporadic service since that time owing to the megachef’s inability to outmaneuver the city’s street-vendor hoop-jumping apparatus, the little green-red-and-yellow cart is back dispensing pastry chef Meredith Kurtzman’s superb gelati in five varieties (it’s $6 for one flavor; $8 for two). New this season: a brownie crumble coppetta. For a fantastic creamsicle effect, the U.G. recommends combining the vanilla gelato with the lemon sorbetto.