Bring 4 quarts of salted water to a boil in a large pasta pot. Cook the orzo for 11 minutes. Drain the orzo, rinsing it briefly with warm water. Place the orzo in a large bowl.

While the orzo is cooking, heat a large skillet over medium heat. Add a glug of olive oil and sauté the diced onion for a few minutes until it starts to brown. Add the zucchini, garlic, and dried oregano. Season with salt and freshly ground black pepper and sauté for 2 to 3 minutes longer, just until the zucchini just starts to soften. Transfer the vegetable mixture to the bowl with the orzo.

Add the spinach, roasted peppers, pine nuts, and Parmesan cheese to the bowl, drizzle in the olive oil and balsamic vinegar, and toss to combine all the ingredients. Season with salt and freshly ground black pepper to taste.

Before serving, stir in the fresh basil and serve warm or at room temperature. This salad can be made up to 2 days before serving.