Step 1

Heat a comal or skillet over medium-low heat. Add the guajillo chiles and toast, turning, until their skin goes from soft and deep red to toasted and mostly browned but not blackened. Transfer the chiles to a saucepan, cover with hot water, and bring to a boil. Reduce the heat to medium, and simmer until the chiles are softened, about 10 minutes.

Step 2

Transfer to a blender, add 1 cup of their cooking liquid, and cover tightly. Puree until smooth.

Step 3

Heat the oil and butter in a large pot over medium heat until the butter melts. Add the onion and cook, stirring occasionally, until it is softened and the edges are just beginning to brown, about 3 minutes. Add the garlic, stir, and cook until fragrant, less than a minute. Raise the heat to high; stir in the mushrooms, 1 tsp. of the salt, and the black pepper, and cook the mushrooms, stirring often. They will release their juices and then, as the juices evaporate, begin to brown, which is what you want. It should take 10 to 12 minutes.

Step 4

Once all of the mushroom liquid has evaporated, reduce the heat to medium, stir in the pureed chiles, and cook until the puree thickens and most of it has been absorbed by the mushrooms, about 10 minutes. Add the broth, stir, add the epazote or cilantro sprigs, and bring to a simmer. Simmer until all the flavors come together, about 10 minutes. Remove the epazote or cilantro, add the remaining 1/2 tsp. salt, and season to taste. Serve with lime wedges.