Heat 4 tablespoons olive oil in a saucepan. Salt drumsticks and fry, turning often, until well browned. Remove drumsticks. Add leeks, onion, garlic and celery heart to the saucepan and lightly fry for 2 minutes, stirring continually.
Add silverbeet and kale. Stir well. Cover vegetables with cold water and add mashed tomatoes and drumsticks. Season with 2-3 good pinches of salt then stir well. Bring soup to the boil then reduce heat to a low simmer. Simmer for 1 hour then turn off heat.
Season to taste. Leave for 1 hour. Serve with plenty of grated parmesan, a drizzle of olive oil and crusty bread. It's even better the next day.