There are many variations of cod stew: A Portuguese one uses salt cod, a Spanish version might contain chorizo, and a French dish exists that includes black olives. What almost all have in common is onions, garlic, potatoes, carrots, celery and/or fennel, and some form of tomato. Here is a basic one from which to elaborate, if you so choose…
Chop finely and saute an onion and a garlic clove in olive oil until soft, and turn off heat. Layer chunky pieces of potatoes, carrots, celery, fennel, and ripe tomatoes on top.* Add a handful of chopped parsley and celery leaves. (Here is where you could add in extra ingredients listed above—chorizo must be cured rather than fresh, and oil-cured black olives are best.) If you cannot find ripe tomatoes, stir a tablespoon of tomato paste into a glass of white wine and pour over vegetables, and then add more white wine until vegetables are covered. Turn on heat again until simmering.
Now salt fresh cod fillets and lay on top (if you use salt cod, prepare it first—see my post “Salt Cod”). Drizzle with olive oil, cover, and place in a 350-degree oven for 30 minutes.
Remove fish (unless using salt cod), cover, and return stew to oven for 30 minutes more. If broth has not thickened, simmer uncovered on stovetop to desired consistency. Taste, season, and serve with the fish.
*This recipe is for a pound of fresh or reconstituted cod; you can decide the ratio of vegetables to fish.