The secret isn't the ice cream, dispensed Mister Softee style, it's the atypical toppings like caramelized bacon, pumpkin butter, olive oil and sea salt, curried toasted coconut, and blueberries with saba (shown on vanilla; $4). Also called vin cotto, saba is a not-so-sweet reduction of unfermented grape pressings that, until now, I'd encountered only in a restaurant setting; it takes well to the out-of-doors.
In summer, the truck typically parks near Union Square. Once the weather turns, perhaps it will follow Mister Softee's lead once again and take a winter break. Time will tell.