In a pot of boiling, salted water, cook the couscous until al dente, 8 to 10 minutes. Drain and rinse with cold water.
Meanwhile, in a large saucepan, heat 2 tablespoons olive oil over high heat. Add the cucumbers and cook, stirring occasionally, until browned, about 5 minutes. Stir in the tomatoes and paprika. Using a food processor, and working in batches, puree the mixture. Return to the pot and stir in the vegetable broth, couscous and zucchini. For cold soup, refrigerate until chilled.
In a small bowl, combine the parsley, parmesan, lemon peel and remaining 1/4 cup olive oil. Serve the soup drizzled with the parsley pesto.