Desalinate the cod correctly in advance if we have bought it salty. Thoroughly clean skin and bones, and crumble or cut into pieces in one bite, if necessary. Reserve.
Wash all the vegetables very well. Finely chop the chives and garlic cloves, chop the celery and cut the peppers without the seeds into small cubes. Cut the zucchini into thick slices -or crescents- and peel the potatoes.
Heat a base of olive oil in a saucepan and sauté the chives with a pinch of salt. Add the garlic and bay leaf when it has taken color, stir a little and add the peppers and celery. Cook for a couple of minutes and add the crushed tomatoes and the chorizo pepper pulp.
Cook for about four or five minutes and add the zucchini, the cascaded potatoes, the paprika and a pinch of salt. Stir well, cover with water or broth, bring to a boil, cover and lower the heat. Let cook for 20-30 minutes, or until the potatoes are very tender. Monitor the liquid level.
Towards the end of cooking, add the cod, stir to integrate it well and correct the liquid level if necessary. Cook a few more minutes, until the fish is done.. If it is very liquid, cook over a high heat uncovered a little at the end. Serve with chopped parsley.