Step 1

Heat the oil in a large soup pot or Dutch oven over medium heat. Add the onions, carrots and celery and cook, stirring often, until the onions are soft and translucent and the vegetables are partially cooked, about 10 minutes. Do not brown; lower the heat if necessary. Stir in the tomato paste and cook, stirring frequently, for 2 minutes more.

Step 2

Add the chicken broth, salt, pepper and bay leaves and bring to a gentle boil. Add the orzo, then reduce the heat to medium-low and simmer for 8 minutes. Add the zucchini and frozen peas. Adjust the heat to bring back to a simmer and cook until the orzo is al dente and the vegetables are all tender-crisp, about 2 minutes more. Remove the bay leaves. Taste and adjust seasoning if necessary (keep in mind that the soup will taste a bit bland before the pesto and Parmigiano-Reggiano are added).

Step 3

Ladle the soup into bowls and garnish with a heaping tablespoon of pesto and grated Parmigiano-Reggiano. Pass more pesto and cheese at the table.

Step 4

Freezer-Friendly Instructions: The soup can be frozen for up to 3 months. Defrost the soup in the refrigerator for 12 hours and then reheat it on the stovetop over medium heat until hot. (The orzo make soak up much of the broth while in the freezer; if necessary, thin the soup out with a bit of water or broth while reheating.)