Grilled Shrimp and Vegetables with Pearl Couscous

Name: Grilled Shrimp and Vegetables with Pearl Couscous
Ingredients: 3 tablespoons red-wine vinegar; 3 tablespoons chopped fresh oregano; 2 tablespoons chopped fresh thyme; 1 large garlic clove, finely chopped; 1 3/4 teaspoons salt; 3/4 teaspoon black pepper; 1/3 cup plus 1/4 cup olive oil; 2 1/4 cups pearl couscous (sometimes called Israeli couscous; 3/4 pound); 1 3/4 cups reduced-sodium chicken broth (14 fl ounces); 1 cup water; 1/4 teaspoon crumbled saffron threads; 2 lb large shrimp (21 to 25 per pound), peeled and deveined if necessary; 2 medium red onions (1 pound total); 2 pounds large zucchini (about 4), cut diagonally into 1/2-inch-thick slices; 6 ounces feta, crumbled (1 1/4 cups); about 12 (8-inch) wooden skewers and 20 wooden picks (round, not flat), soaked in water 30 minutes