Add oregano (whole sprigs or leaves, stripped and chopped), bay leaf, tomatoes, white wine, and stock. Stir and simmer over low heat until the broth reduces in volume by about half. Season to taste with salt, pepper, and crushed red pepper. Remove the bay leaves and oregano stems (if using).*
Immediately prior to serving, bring the base to a simmer. Add clams and fish, and cover. Once the clams start to open, add the shrimp and crab.
Serve as soon as the seafood is just cooked through.
Serve with a thick slice of buttered sourdough toast.
Notes
Soup base can be made ahead of time and kept in the refrigerator overnight or frozen for longer-term storage. If you do cannot find Dungeness crab, you can substitute snow crab clusters or omit.
Recipe by The Taste Edit at https://thetasteedit.com/cioppino/