Grilled Beef and Vegetable Kebabs

Name: Grilled Beef and Vegetable Kebabs
Ingredients: Marinade:; 1 onion (chopped); 6 garlic cloves (chopped); lemon zest from one lemon; 2 Tablespoons fresh rosemary or thyme (chopped); 1/3 cup beef or chicken broth; 1/3 cup vegetable or canola oil; 3 Tablespoons tomato paste; 2 teaspoons table salt; 1 1/2 teaspoons sugar; 3/4 teaspoon ground black pepper; Kebabs:; 2 lbs sirloin steak tips (cut into 1 1/2 - 2 inch cubes); 1 zucchini (about 1/2 - 3/4 lb); 1 large red bell pepper; 1 large red onion