Combine onion, carrot, celery, garlic, 2 tbsp of parsley, thyme, water/stock and peppercorns in a large saucepan over medium to high heat. Bring to the boil. Reduce heat to low and simmer for 30 minutes.
Add silverbeet and simmer for a further 10 minutes.
Add cooked chicken to saucepan. Simmer for a further 2 minutes until chicken is thoroughly heated.