Shrimp with Zucchini and Spicy Couscous

Name: Shrimp with Zucchini and Spicy Couscous
Ingredients: 2 tablespoons extra-virgin olive oil; 1 small onion, thinly sliced (1 cup); Kosher salt (we use Diamond Crystal) and freshly ground pepper; 1 zucchini, halved lengthwise and cut into ¼-inch-thick slices (2 cups); 1 cup green salsa, such as Xochitl, plus more for serving; 1 can (4.5ounces) chopped mild green chiles, such as Old El Paso; 1 cup couscous; 1 pound peeled, deveined large shrimp; ½ cup frozen peas; Sour cream and sliced radishes, for serving