The cheung fun cart might be the hot-dog-and-pretzel stand of Chinatown, only cheaper and less tourist-friendly. The steamed rolled rice noodles, snipped with scissors, topped with your choice of spongy curried fish balls, soft, ultra-fatty pork skin, or tripe, and doused with a quartet of sweet and spicy sauces, is a popular sidewalk snack everywhere from Elizabeth Street to Pike Street. You won’t pay more than a buck or two, depending on serving size (a smaller Styrofoam container or larger plastic pint cup). The proprietress of this one has been manning her bustling cart just off Bowery for at least twenty years, and she’s done well enough to open a four-items-for-$3 joint on Eldridge Street, where the cheung fun is offered for breakfast. Besides the ever-popular rice noodles, the cart also dispenses mei fun and the string-tied, leaf-wrapped sticky rice packets called joong, all of which can be enjoyed alfresco at the Hester Street Playground down the block, where the handball games are fast and furious.