Tabbouleh with Grilled Vegetables

Name: Tabbouleh with Grilled Vegetables
Ingredients: 1 cup bulgur; ¾ teaspoon salt, divided; 1 cup boiling water; 2 medium zucchini, cut lengthwise into 1/2-inch-thick slabs; 2 sweet onions, such as Vidalia, cut into 1/2-inch-thick rounds; 3 large portobello mushroom caps, wiped clean; 2 cups cherry tomatoes; 3 tablespoons extra-virgin olive oil, divided; Freshly ground pepper, to taste; ¼ cup chopped walnuts; 3 tablespoons lemon juice; ½ cup chopped fresh parsley; ½ cup chopped fresh mint