Grilled Vegetables With Couscous and Yogurt Sauce

Name: Grilled Vegetables With Couscous and Yogurt Sauce
Ingredients: 2 bell peppers (any color), stemmed, seeded and quartered; 1 yellow squash, sliced into 1/4-inch-thick rounds; 8 ounces shiitake mushrooms, stemmed; 2 cloves garlic, unpeeled; 2 to 3 sprigs thyme, rosemary or oregano; 3 tablespoons extra-virgin olive oil, plus more for brushing; Kosher salt and freshly ground pepper; 1 large red onion, sliced into 1/4-inch-thick rounds; 1 10-ounce package couscous; 1/2 cup 2% Greek yogurt; 1/4 cup sliced almonds, toasted