Tanzanian green banana and beef soup (Mtori)

1. Bring the beef to the boil with the water, the halved onion and the salt, skim off the foam, cover and simmer for 45 minutes.

2. Peel the green plantains (with oiled hands) and cut into 3 cm pieces; dice the tomatoes.

3. Add the plantains, tomatoes and crushed garlic to the soup and cook for another 20 minutes until the plantains are completely soft.

4. Lift out the meat and chop it finely; discard the onion.

5. Purée the soup until smooth with a stick blender, return the meat, pour in the milk, stir in the butter and heat until just boiling.

6. Season with pepper and serve hot.

Tip: Mtori is the creamy soup of the Chagga people living on the slopes of Kilimanjaro; it is traditionally made for new mothers to build up their strength. Be sure to use green, unripe plantains, ripe ones would make it sweet. You can use coconut milk instead of milk.