cioppino recipe

2 tablespoons olive oil 1 large onion, chopped 2 cloves garlic, minced 1 fennel bulb, chopped (optional) 1 teaspoon red pepper flakes (optional, for a bit of heat) 1 can (28 oz) crushed tomatoes 1 cup dry white wine 4 cups seafood or fish stock (or chicken broth) 1 bay leaf 1 teaspoon dried oregano