Heat olive oil in large soup potAdd onions and carrots and cook until translucent (about 5 minutes)Add garlic and cook for one minuteAdd oregano, chili powder, cumin, salt and pepperIn a blender, puree tomatoes and pasilla pepper, add to potStir in chicken broth. Simmer for ½ hour then add cooked chicken and corn.Simmer until flavors have blended. Re-season if necessary and serve.