The Thai dessert of threaded egg yolks in syrup, of Portuguese origin, is Foi Thong. Its name means “golden strands,” referring to the dessert’s long, shiny yellow threads.
To make it, beaten egg yolks are poured in extremely thin streams into hot sugar syrup. The yolk forms delicate strands that are gathered into nests, bundles, or coils. In Thailand, foi thong is served as a refined sweet and is especially associated with auspicious occasions; the word thong, meaning gold, carries positive connotations.
The dessert belongs to a wider Portuguese tradition called fios de ovos, literally “egg threads.” Portuguese convent kitchens are often associated with egg-yolk sweets because cooks used egg whites for starching clothes, leaving surplus yolks. The technique spread through Portuguese trade and colonial networks to parts of Asia.
In Thailand, the recipe is traditionally linked to Maria Guyomar de Pinha, a Thai-born woman of Portuguese and Japanese ancestry who served in the Ayutthaya court. Foi Thong is related to other Thai “golden” sweets, including Thong Yip and Thong Yot, but those have different shapes and preparations.