Chop the tomatoes and peel and crush the garlic cloves. Fry half of the tomatoes, the garlic, the onion and all of the spices in a little butter and oil.
Mix in the remaining tomatoes and the potatoes. Let it sauté for a couple more minutes.
Pour in the water and add the bouillon. Leave it to simmer until the potatoes are soft.
Mix in the chopped chorizo sausages and season with salt and pepper.
Carefully add the fish ten minutes before serving, adding a final dollop of yogurt.