Jiandui or sesame balls are a type of fried Chinese pastry made from glutinous rice flour. The pastry is coated with sesame seeds on the outside and is crisp and chewy after immediately being cooked. Inside the pastry is a large hollow, caused by the expansion of the dough. The hollow of the pastry is filled with a filling usually consisting of lotus paste, or alternatively, sweet black bean paste, or red bean paste.

Depending on the region and cultural area, jiandui are known as matuan (麻糰) in North and Northwest China, mayuan (麻圆) in Northeast China, and zhendai (珍袋) in Hainan.^{[citation needed]}

The origins of jian dui can be traced back to the Tang dynasty as a royal food in Chang'an, known as lüdui (碌䭔). This food item was also recalled in a poem by the Tang poet Wang Fanzhi. With the southward migration of many peoples from central China since the An–Shi Rebellion, the jian dui was brought along and hence became part of southern Chinese cuisine.

In Hong Kong, it is one of the most standard pastries. It can also be found in most Chinatown bakery shops overseas.

In Japan, it is known as goma dango (ごま団子; sesame dumpling). It is often sold at street fairs, in Chinese districts, and at various restaurants.

In Korea, it is called jungguksik chamkkaegyeongdan (중국식 참깨경단, "Chinese-style sesame rice ball cake"), to avoid confusion with the Korean-style sesame rice ball cake (chamkkae-gyeongdan) with sesame coating. As the Chinese jian dui is first coated with sesame seeds then deep-fried, while the Korean gyeongdan is first boiled then coated with toasted sesame seeds, jian dui is also called twigin chamkkaegyeongdan (튀긴 참깨경단, "deep-fried sesame rice ball cake").

The pastry is called num kroch or nom kroch (Khmer: នំក្រូច, lit. 'orange cake' due to its shape resembling the fruit) in Khmer and was introduced in Cambodia by Chinese migrants.

In Indonesian cuisine, it is called onde-onde or kue moci, filled with sweetened mung bean paste. People usually eat it as a snack. This pastry is also popular and widely available in Indo (Eurasian), Indonesian, and Vietnamese outlets in the Netherlands.