On an ungreased skillet or griddle set over medium heat, roast the chiles and garlic, turning everything regularly, until they are soft and darkened in spots—most everything should be done in about 10 minutes. Let them cool to room temperature, then slip off the skins from the garlic. If you have a mortar, crush the chiles and garlic together until the mixture looks like a rough paste. Otherwise, chop them in a food processor. Scrape the mixture into a salsa dish, then stir in the lime juice and enough water to give it the texture of a thinnish salsa (it’s really spicy, so it’s wise to not make it thick). Stir in ½ teaspoon of salt, then taste it cautiously (a drop will usually be enough). Add more salt if necessary to balance the heat and acid.