This salsa, known as salsa de habanero tatemado, is made with only four ingredients (not including the water and salt), but its flavor is amazingly complex—at once fruity, spicy, bitter, tangy and subtly sweet—owing mostly to the intense charring (scorching, really) of the chilies and alliums. The deep char also makes the salsa black in color. (Charring takes place on the stovetop, so you may wish to turn on the hood and/or open a window during cooking.) We adapted the recipe taught to us by Josefina López Méndez, chef at Chapulín restaurant in Mexico City. The habaneros are kept whole for easier turning; for heat seekers, after charring, before blending, leave the seeds in all of the chilies, but for more timid palates, consider removing some or all of the seeds. Just a little of this fiery salsa goes a long way, so add it judiciously.