Place the chorizo in a food processor and process until the pieces are small and well ground up. Heat a Dutch oven or a large pot over medium heat and add the ground chorizo to cook until well colored and fat is rendered. Meanwhile add the garlic, celery and hand crushed tomatoes to the pot.
Once the ground chorizo is cooked, add the vegetable puree, thyme and bay leaves and sauté for a further 5-7 minutes. When the liquid has cooked off a little, dust with the flour and stir well – this forms the base of a roux, which is a cooked mixture of fat and flour that functions as a thickener. Then add the red wine, reserved tomato juice, and chicken stock. Season lightly with salt and pepper and then cover and simmer for 2 hours.
With 10 minutes to go, turn the heat up and add the clams to the broth and steam until open, discarding any that are still closed as they are not safe to eat. Reduce the heat. Just prior to serving, add the shrimp and promptly shut off the heat so they don't over cook.
Meanwhile prepare the fish by seasoning the filets with salt and pepper and fresh thyme. Heat a large sauté pan and add the olive oil and butter. Cook filets 4 minutes per side and then serve in large flat bowls. Over the cod, ladle the stew or cioppino. Finish with some more broth a handful of chopped Italian parsley. Serve with garlic bread as desired.