Step 1

In a large saucepan over medium-high heat, combine the chicken, broth, tomatoes and their juices, and orzo. Bring to a boil, then reduce the heat to medium-low and cook, stirring occasionally, for about 8 minutes.

Step 2

Grate 1 teaspoon of zest from the lemon (about half a lemon's worth) directly into the pot, then cut the fruit in half and squeeze in 1 tablespoon of its juice. Stir in the zucchini and/or yellow squash and cook until tender, 3 to 4 minutes. The chicken should be cooked through.

Step 3

Taste, and season lightly with salt and pepper if you are using the basil-and-garlic-flavored tomatoes; season with about 1/2 teaspoon of salt, or to taste, and a few grinds of pepper, if you are using fresh or no-salt-added tomatoes.

Step 4

Remove from the heat and divide among individual bowls. Top each portion with the pesto, to taste. Cut the remaining lemon half into wedges, for squeezing over, and serve.