Enchilada Sauce "Salsa Negra"
Pasilla chile peppers are long and slightly wrinkled. Do not confuse them with ancho chiles. If you cannot find them, you can substitute guajillo chiles, but the sauce will not be as dark.
Traditional enchiladas are made with lightly-fried corn tortillas, never flour tortillas. Place some sauce in the bottom of a baking dish, arrange the enchiladas in rows and cover with more sauce and cheese before baking.