Take the fish out and transfer the vegetables into the food processor (set aside several pumpkin cubes for serving). Separate the leaves from the rosemary and mix them in with the vegetables, dispose of the stem.
Take the fish out of the packaging and cut it into halves. Peel the onion and the garlic and cut them into quarters. Put 2 tablespoons of olive oil, the celery stalk, rosemary, onion, pumpkin and a pinch of salt into a pot.
Sautée on medium heat until the vegetables release their aroma and start sticking to the bottom of the pot. Add the garlic and sautée for one more minute. Add some cold water. Add the fish and cook for 15–20 minutes. Take the fish out and transfer the vegetables into the food processor (set aside several pumpkin cubes for serving). Separate the leaves from the rosemary and mix them in with the vegetables, dispose of the stem. Process the vegetables into a purée, then put the purée back into the previously strained soup. Add some more salt, pepper and the rice, then cook. In the meantime, remove the head, bones and skin from the fish and discard. Slice the fish and add it to the soup once the rice is done. Bon appétit