1. Preheat oven to 400°.
2. To prepare rouille, combine roasted red bell peppers and mayonnaise in a blender or food processor; process until smooth. Set aside.
3. To prepare the croutons, arrange baguette slices in a single layer on a baking sheet; bake slices at 400° for 8 minutes or until toasted. Rub one side of each crouton with cut side of garlic clove halves; discard garlic clove halves. Set croutons aside.
4. To prepare bouillabaisse, heat oil in a large Dutch oven over medium heat. Add onion and garlic to pan; cook 8 minutes or until tender. Add tomato; cook 3 minutes. Add saffron; cook 30 seconds. Add potato, fennel, clam juice, and broth; bring to a boil. Cover, reduce heat, and simmer 10 minutes or until potato is almost done. Increase heat to medium. Add clams; cover and simmer 5 minutes. Add mussels; cover and simmer 3 minutes. Add shrimp and fish; cover and simmer 5 minutes or until shells open, shrimp is done, and fish flakes easily with a fork or until desired degree of doneness. Discard any unopened shells.
5. Ladle 2 cups seafood mixture into each of 6 shallow bowls. Spread each crouton with about 1 tablespoon rouille. Place 1 crouton on top of each bowl; sprinkle each serving with 1 tablespoon parsley.