Sweet-n-Tart started out in a small space at 76 Mott Street, at Canal Street. It was an instant hit at the time, as it was the first restaurant to serve the Chinese "tong shui" (sweet dessert soups such as red bean soup, ground almond or sesame paste etc) as well as cold drinks such as juice combinations with tapioca and the likes. Note that this was before the bubble-tea movement even hit New York! Now the restaurant has 3 locations, with two in the city (20 Mott Street is much larger and the upstairs is nicely decorated) and one in Flushing.
This is more of a lunch and afternoon snack place although dinner is served and more substantial dinner-type dishes are on the menu. This is also a popular stop during the summer months to grab a cold drink. They serve thirst-quenchers such as watermelon ice, honeydew juice, papaya milkshake and other mixtures with funny names like the Titatnic (3 juices mixed together with tapioca.) In the winter, the hot dessert tonics are very popular, all throughout the day or after dinner.
The menu is long and has a variety of Cantonese dishes. There are sections on dim sum, noodles, rice, as well as small plates of cold and hot dishes (kind of like chinese tapas.) You can find staples such as wonton noodle soup, spare ribs over rice as well as more exotic but authentic appetizers such as braised ducks' tongues and thousand year old eggs. One of my favorites is the noodle soup with shrimp and watercress dumplings. They are like wontons with the addition of watercress.
Credit cards are accepted and except during weekends and prime lunch hours, tables are usually available quickly as turnover is fast.