Heat the 1 Tbs. oil in a medium (3-quart) saucepan over medium heat. Add the onion and cook, stirring occasionally with a wooden spoon, until softened and just beginning to brown, 3 to 5 minutes.
Add the chili powder and tomato paste and cook, stirring, for 15 to 30 seconds; don’t let the chili powder scorch.
Pour in the broth and bring to a simmer.
Reduce heat and simmer for 20 minutes.
While the soup simmers, fry or bake the tortilla chips.
Divide the soup into bowls and top with turkey, tomato, corn, black beans, avocado, cheese, cilantro, and a squeeze of lime juice.
Serve immediately with tortilla chips.