To make the salsa, char peppers over an open flame or under a hot broiler. Place fully charred peppers in bowl, cover with plastic wrap until cool. Peel, seed and reserve.
Heat oil, about 2 tablespoons, in a skillet over medium-high heat. Add onions and garlic, and stir a few minutes. Add tomatillos, cumin, coriander, salt and pepper, and cook 10 minutes more until a sauce forms and thickens. Add mixture to a food processor or blender with lime juice and honey. Process until fairly smooth.
For posole, heat oil, about 3 tablespoons, in a soup pot or Dutch oven over medium-high heat. Add mushrooms and brown well, 15 minutes. Season with salt and pepper, cumin, coriander, oregano, epazote if using, and stir a minute more. Deglaze with beer. Add salsa, hominy and stock, and simmer over low heat until ready to serve.
Serve in shallow bowls topped with garnishes and charred tortillas on side.