Caldo de piedraFish and tomato stone soup
Caldo de piedra comes from San Felipe Usila in the Chinantla of northern Oaxaca, where Chinantec men cook it by the river: fish, tomato, chilli and epazote go into a gourd bowl of water and red-hot river stones are dropped in to bring it to a fierce boil in seconds. It is eaten as a celebration and every year at a festival in the village. Heating stones at home is dangerous (wet or porous stones can crack or burst), so this version brings a heavy pot to a hard boil first and cooks the fish just as briefly. A portion gives about 38 g of protein, from the fish and prawns, for roughly 260 kcal. The common mistake is letting the fish boil on: it is done in 3–4 minutes, when it turns opaque and flakes, and after that it falls apart. Chef's tip: blend the tomato, onion and chilli raw; the broth tastes fresh and sharp, closer to the riverside original than a cooked sauce.























