1Heat the olive oil in a large pot over medium heat.
Add the diced onions, carrots, and celery. Sauté until the vegetables are softened, about 5-7 minutes.
Add the diced potatoes and cook for another 5 minutes.
Pour in the tomato sauce and fish stock. Stir to combine.
Season with salt, black pepper, and rosemary. Bring the mixture to a simmer.
Add the mixed seafood to the pot. Cover and cook until the seafood is cooked through, about 5-7 minutes.
Taste and adjust seasoning if necessary.
Serve hot with crusty bread or over rice.