Step 1 Place a large saucepan over medium heat. Add olive oil and heat. Add leek and capsicum; cook, stirring, for 5 minutes, or until soft. Add garlic and cook, stirring, for 1 minute.
Step 2 Add tomatoes, stock, tomato paste, orange juice and thyme to saucepan with 1 cup water; bring to the boil. Reduce heat to low, cover and simmer for 5 minutes. Add risoni; simmer, covered, for 10 minutes.
Step 3 Add prawns and all of the fish to saucepan. Increase heat to medium; bring back to the boil. Reduce heat to low, cover and simmer gently for 4–5 minutes, or until seafood just cooks through. Add frozen green beans and cook for another 1–2 minutes, or until beans heat through.
Step 4 Scatter seafood stew with extra thyme leaves and serve.