Yan ju ji (盐焗鸡, salt-baked chicken) is a preparation associated with the Hakka people (客家人, a sub-group of Han Chinese who migrated from the north to Guangdong, Fujian, and Taiwan over centuries) — a whole chicken wrapped in paper and baked in a wok or pot filled with 2-3kg of preheated, coarse salt. The salt acts as a heat medium — an even, enveloping heat that cooks the chicken slowly from all sides simultaneously, producing an extremely tender, evenly cooked bird with a distinctly fragrant and slightly salty skin flavour.
The preparation: The whole chicken is first marinated in a dry mixture of sand ginger powder (sha jiang, 沙姜, a variety of galangal that is essential to the Hakka flavour), salt, and Shaoxing wine. Rub the marinade into the cavity and all over the exterior. Air-dry in the refrigerator uncovered for at least 4 hours — preferably overnight. The wrapping: Wrap the chicken in two layers of parchment paper (parchment, not greaseproof). The paper prevents direct contact with the salt and allows slow, even steam cooking within the paper. The salt baking: Heat 2-3kg coarse salt in a large wok or pot until very hot (the salt will steam slightly when a drop of water is added — approximately 200C). Bury the wrapped chicken in the salt. Cover. Bake 45-60 minutes for a 1.5kg chicken. The salt maintains an even temperature throughout the cooking period.
Eileen Yin-Fei Lo, Mastering the Art of Chinese Cooking (2009); Fuchsia Dunlop, Land of Fish and Rice (2016)