Beef and Vegetable Shish Kebabs

Name: Beef and Vegetable Shish Kebabs
Ingredients: 1 tablespoon kosher salt; 2 teaspoons packed light brown sugar; 1 teaspoon finely grated lemon zest (from about 1 medium lemon); 1/2 teaspoon ground cumin; 1/2 teaspoon paprika; 1/4 teaspoon freshly ground black pepper; 1/4 teaspoon ground coriander; 1/3 cup olive oil; 2 tablespoons tomato paste; 5 medium garlic cloves, finely chopped; 1 (1-1/2- to 2-pound) sirloin steak, about 1 inch thick; 8 ounces cremini mushrooms; 1 pound summer squash (zucchini, yellow, or a mixture of both); 1 medium red onion; 10 (12-inch) wooden or metal skewers (soak wooden skewers in water for 30 minutes to avoid burning on the grill)