How to Make It
Heat a large cast-iron skillet over high. Add corn; cook, stirring occasionally, until lightly charred, 4 to 5 minutes. (Some kernels may pop out of the skillet.) Remove corn from skillet; set aside.
Add oil to skillet; heat 30 seconds. Add mushrooms, oregano, ancho chile powder, and cumin. Cook, stirring often, until mushrooms begin to brown, 2 to 3 minutes. Stir in garlic and salt, and reduce heat to medium. Cook, stirring occasionally, until mushrooms are tender but still somewhat firm, 2 to 3 minutes. Remove from heat, and stir in corn.
Place a generous ½ cup mushroom mixture in each tortilla. Top each with 2 tablespoons onion, 1½ tablespoons salsa, a few chile slices, and cilantro leaves.