Place tomatoes, undrained, in a non-reactive mixing bowl; shred by hand, discarding any skin and hard cores. Set aside.

Clean onions; halve lengthwise and thinly slice. Thinly slice green onions; set aside a handful of green tops for garnish. Clean and dice bell pepper. Place a large, heavy saucepan over medium-high heat; add olive oil. when hot, add onion, green onions, bell pepper, celery, bay leaf, oregano, and hot pepper flakes and cook, stirring, until onion softens, about 8 minutes. Add garlic and cook until fragrant. Add tomato paste and anchovy paste and cook for 2 minutes; deglaze pan with a little of the wine.

Add remaining wine to pan, bring to a boil and cook, stirring, until wine reduces by half, about 5 minutes. Add reserved tomatoes and juice, seafood stock or clam juice, and chicken broth; bring to a simmer, cover, and cook for 30 minutes. Season with salt and pepper; remove and discard bay leaf.

Rouille:

Clean garlic cloves; finely dice. Sprinkle with a pinch of coarse salt and, using the flat side of a chef's knife, mash into a pulp; transfer to a blender or food processor. Tear bread into pieces and add to garlic; process until very finely chopped. Add the egg yolk, lemon juice, saffron, and cayenne pepper and process until combined. While processing, add olive oil in a very thin, steady stream to emulsify; this should take at least I minute. Add salt and pepper to taste; refrigerate until ready to use.

Add crabs, clams, and mussels to pan and continue to simmer; remove clams and mussels to a bowl as they open and reserve. Add fish, shrimp, scallops, and crawfish tails to pan and simmer until just cooked through, about 5 minutes.

Divide reserved clams, mussels, and remaining seafood evenly among 6 large soup bowls; ladle broth over seafood. Garnish with parsley and basil, and serve at once with garlic croutons spread with rouille.