Caldo de piedra, “stone soup” is a traditional dish of the chinanteco ethnic group of Oaxaca and dates back to prehispanic times. This group lives by the shores of the Papaloapan river and developed a special way to prepare their food using river rocks heated in the fire.
To make the stone soup, fish or seafood is placed in a gourd bowl along with a tomato-based broth and seasonings, then a hot river rock taken directly from the fire is placed in the gourd, where it sizzles and cooks the soup in an instant.
A few upscale restaurants in Oaxaca have started serving caldo de piedra, but for the traditional chinanteco version, visit the palapa located on the road out towards Santa Maria del Tule. There a chinanteco family has set up a small restaurant serving caldo de piedra as well as quesadillas.