- Boil the vegetable broth with the fish bones and heads, along with the star anise.
- Strain the broth and set it aside.
- In a food processor, blend the fish fillets, onion, and dill.
- Add the rice, olive oil, lemon zest, and season with salt and pepper.
- Mix well and form small balls from the mixture.
- Carefully drop the fish balls into the hot broth with a spoon, and simmer on low heat for 20-25 minutes.
- Finally, thicken the soup by mixing the vinegar, lemon juice, and corn flour in a bowl.
- Just before turning off the heat, add this mixture and stir gently.