In a large non-stick or well seasoned skillet over medium-high heat, combine the zucchini and onion with olive oil and salt. Cook, stirring a few times until the veggies turn golden brown, about 10 minutes. Don't stir too often so the veggies have time to brown.
Add the stock to the skillet and bring to a simmer. Stir in the orzo, lemon zest and ½ teaspoon salt. Cover and simmer over medium-low heat until the orzo is nearly cooked through and most of the liquid is absorbed, about 10 to 12 minutes, stirring occasionally.
Meanwhile, in a small bowl, toss together the tomatoes and mozzarella. Add a pinch of salt and drizzle a little extra virgin olive oil. Let it marinate while the orzo cooks.
Once the orzo is ready, stir in the juice of ½ lemon, Parmesan and pesto. Cover and continue simmering for about a minute or 2 to finish cooking. Taste for seasoning and add more lemon juice or pesto if needed.
Remove the lid and add the tomatoes and mozzarella. Sprinkle a little Parmesan over the top and serve immediately.
Notes
*This recipe was adapted from Melissa Clark's Pesto Orzo Zucchini recipe posted in the New York Times Cooking, July, 2023