Our trip to Taquería Los Parados in Roma Sur last month began like any other: we gathered up four friends and began the trek to this beloved taco spot. But the dark, moody sky threatened rain, and in anticipation of a gushing downpour, we piled into a cab minutes before the first giant, icy cold rain drops began to pelt down.As was so often the case on July and August evenings in Mexico City, we were at the mercy of the Aztec rain god Tlaloc.Our destination, Los Parados, is one on a short . . .