Heat a large pot over medium heat.

Add the chorizo and cook until browned, about 5 minutes.

Add the garlic and onion and cook until softened, about 5 minutes.

Stir in the kale, potatoes, tomatoes, and water.

Bring the mixture to a boil.

Reduce heat to low, cover the pot, and simmer for 20 minutes, stirring occasionally.

Remove the lid, increase the heat slightly, and cook for another 20 minutes.

Stir in the salt and pepper.

Gently place the cod fillets over the stew liquid.

Cover the pot and simmer until the cod is cooked through, about 5 minutes.

Carefully transfer the cod fillets to shallow soup bowls using a wide spatula.

Spoon the stew over the cod and serve immediately.