Roasted Jalapeño Sauce

This simple but delicious sauce appears on the table with almost everything at La Pereñita, one of the most famous restaurant stands in the 20 de noviembre market in Oaxaca City. The owner, Nicolasa Ramirez, insists that the secret is to boil and then cool the water—she swears it does not taste the same if you make it with plain tap or bottled water.

The sauce as I had it was thin, very smooth-textured, and hotter than hell from the good local jalapeños. If preferre