In a large pot, heat oil and butter until butter is melted.
Add bell pepper, celery, onion and garlic. Saute until softened.
Add flour. Saute for 2 minutes, until flour is no longer raw.
Add broth and milk. Bring to a boil.
Add potatoes, bay leaf and spices. Simmer until potatoes are cooked through, about 20 minutes.
Add clams with their juice. Simmer another 5 minutes.