This sauce is tarter when made with tomatillos.
- 5 ripe plum tomatoes or 7 medium tomatillos, husked and washed
- 6 dried árbol chiles, stemmed
- 2 cloves garlic, crushed and peeled
- 1⁄4 tsp. sugar (optional)
Preheat broiler and set rack about 4'' from the heat. Arrange tomatoes or tomatillos on a baking sheet and broil until soft, blackened, and blistered, turning once, about 8 minutes per side. Set aside to cool completely.
Meanwhile, heat a small skillet over medium heat until hot but not smoking. Add chiles and toast, stirring constantly, until aromatic and lightly browned in spots, 30-45 seconds. Transfer chiles to jar of a blender. Add garlic and broiled tomatoes or tomatillos, along with any caramelized juices. Blend to a smooth purée with flecks of chiles, then transfer to a medium bowl.
To thin sauce, add up to 1⁄2 cup water. Season to taste with salt and sugar. Serve with huarachitos (see recipe), if you like.