The answer is: monk fruit

Monk fruit, also known as Luo Han Guo, is a small, green gourd native to southern China and northern Thailand. It is well-known for its natural sweetness and is commonly used as a sugar substitute in the form of monk fruit extract or sweetener. The sweetness comes from compounds called mogrosides, which are much sweeter than sugar but contain no calories, making monk fruit a popular choice for those seeking a healthier alternative to refined sugar. Additionally, it has been traditionally used in Chinese medicine for its potential health benefits, such as soothing sore throats and supporting respiratory health.