Warm olive oil in a large pot set over medium-high heat (warm the pot first to prevent scorching the oil).
When oil begins to shimmer, add onion and garlic; cook until onion pieces are browned and soft. Add zucchini, chicken broth, stewed tomatoes, tomato sauce, corn, cumin and black pepper.
Cover pot and bring to a boil; reduce heat and let simmer, covered, for 30 minutes (stirring occasionally).
Spoon soup into bowls; top each bowl with tortilla chips and Cheddar cheese.Makes 5 quarts Source: