In a large saucepan, combine broth, chicken, undrained tomatoes, and uncooked orzo. Bring to boiling; reduce heat. Simmer for 6 minutes.
Add zucchini, lemon peel, and lemon juice. Return to boiling; reduce heat. Simmer, uncovered, for 3 to 4 minutes or until orzo and zucchini are tender and chicken is no longer pink. Season to taste with black pepper. Top each serving with pesto. Makes 4 to 6 servings.