Thaw halibut and scallops, if frozen. Cut halibut into 1-inch pieces and cut large scallops in half or quarters; set aside. In a large saucepan, heat oil over medium heat. Add onion, sweet pepper, and garlic; cook about 5 minutes or until tender, stirring occasionally. Stir in tomatoes, vegetable broth, the water, corn, cumin, and ground black pepper. Bring to boiling; reduce heat. Cover and simmer for 10 minutes.