Place first 5 ingredients on a double layer of cheesecloth. Gather edges of cheesecloth together; tie securely.
Heat 1 teaspoon oil in a large Dutch oven coated with cooking spray over medium-high heat. Add onion and celery; sauté 3 minutes or until tender. Add garlic; sauté 1 minute. Add wine, and cook 1 to 2 minutes or until liquid evaporates, scraping pan to loosen browned bits. Add cheesecloth bag, tomatoes, and next 4 ingredients; bring to a boil. Reduce heat to low, and simmer, uncovered, 35 minutes.
While stew simmers, combine basil and next 4 ingredients in a food processor; process until smooth. Spoon pistou into a small bowl; set aside.
Remove cheesecloth bag from stew, and discard. Bring stew to a boil. Stir in fish and scallops; cover and cook 2 minutes. Stir in shrimp; cover and cook 3 minutes or until seafood is done. Ladle soup into bowls, and top with pistou.