Steps
1. Wash and roughly cut the tomatoes, carrot, turnip, onion and green pepper, and fry lightly in butter, with ground peppercorns (if used).
2. Add stock, herbs and salt and simmer until vegetables are cooked thoroughly and soft.
3. Strain through a fine sieve.
4. Mix flour or cornstarch to a smooth paste with cold water, add to soup and boil for 5 minutes.
5. Add milk and reheat without boiling.
6. Season to taste and colour if necessary.
7. Serve hot with fried croutons.

Source
Food and Agriculture Organization of the United Nations (1991), Post-harvest and processing technologies of African staple foods: a technical compendium, ISBN 92-5-103076-6, Rome