On the one hand, in a city with as many top-shelf restaurants as the Mexican capital, it seems silly to privilege a hotel restaurant among those you should definitely patronize.
On the other hand, the food at Diana, the restaurant in the St. Regis, is really that good. The spacious restaurant is comfortable and welcoming, and the kitchen specializes in contemporary Mexican cuisine, with most dishes drawing almost exclusively on local ingredients.
The restaurant is named for the huntress Diana, who stands atop a fountain on Avenida Reforma, bow drawn. Either before or after your meal, spring for a nightcap at the hotel's King Cole Bar, which has a terrace offering a direct view of Diana.
Chocolate and churros are a favorite Mexican dessert, and you can order the delicious duo at dozens of restaurants around Mexico City.
The contemporary twist on chocolate and churros at the Restaurante Diana in the St. Regis, though, is pretty great, not the least reason being that it comes with a wonderful view of Avenida Reforma and the round-about featuring the Diana the Huntress Fountain.