Step 1

Heat oil in a Dutch oven or large soup pot over medium-high heat. Add leeks and cook, stirring occasionally, until soft, about 3 minutes. Add broth, water, potato, thyme, salt and pepper. Bring to a boil, reduce heat to low and simmer, covered, for 5 minutes.

Step 2

Add orzo and cook, partially covered, stirring occasionally to prevent sticking, for 5 minutes. Add beans and zucchini and continue to cook, partially covered, until the vegetables and pasta are tender, about 8 minutes more.

Step 3

Stir in spinach and cook, stirring, until wilted, about 2 minutes. Season the soup with vinegar. Ladle into bowls and garnish with Parmesan.