Heat olive oil in a 12" skillet over medium-high heat. Add the onion and cook until slightly caramelized, 6-7 minutes. Add the mushrooms and garlic and cook until mushrooms are browned, about 5 minutes. Stir in soy sauce, chipotle peppers and sauce, corn kernels, chard, salt, and pepper; cover pan with lid and cook, stirring occasionally, until chard wilts, about 5 minutes.
Spoon mixture into tortillas and top with cilantro and sour cream. Serve with lime wedges, if you like.