Uji

Fermenting depends on the good bacteria beating the bad ones. Wash your hands, the container and the spoon in hot water before you start.

Use finger millet flour (wimbi). Sorghum or maize also work, but millet is the most valued for children's uji because it is rich in minerals.

Stir the flour into lukewarm water until there are no lumps. Start with a little water, then add more — pour it all in at once and you will get lumps that never go away.

Cover the container with a clean cloth that lets a little air through. A completely airtight lid shuts out air and changes the fermentation.

Keep it at ordinary room warmth, around 25-30 °C, for 48 hours. Somewhere cool it will take three days or more.

Stir morning and evening with a clean spoon. This helps the bacteria spread through the whole mixture.

You will see a little foam on top and smell a sourness like fermented milk. The smell should be sour, not rotten.

If you see coloured mould (green, black, pink) or smell rot, discard the lot. Do not try to scoop out the spoiled part — safety first.

Pass it through a sieve or a thin cloth to remove bran and lumps. Smooth uji comes from straining, not from long cooking.

Put a litre of clean water on to boil properly. The water must be boiling before you pour the mixture in.

Pour the mixture into the boiling water slowly, stirring without stopping. Stop stirring for even a few seconds and you will get lumps.

Lower the heat and keep stirring for 15 minutes until the uji thickens and turns glossy. Undercooked uji tastes of raw flour.

Add a little sugar, honey, or lemon juice to taste. Some people add milk; some drink it just as it is.

Grains have their own defences. Millet, sorghum and maize contain something called phytate, which binds iron and zinc and stops the body absorbing them. This is not a grandmother's tale — it is established by scientific research. The natural bacteria at work during fermentation release an enzyme that breaks phytate down, freeing the minerals. Fermented uji delivers considerably more usable iron than the identical uji unfermented. That is the real reason behind the custom.

Safety too. Lactic acid bacteria lower the acidity (pH), and in those conditions disease-causing bacteria cannot grow. In places without refrigeration, fermenting is a way of preserving food — not merely a matter of flavour.

Uji is food for children and for the old. Uji has long been the first food for a child being weaned in East Africa. It is smooth, easily digested, and full of energy. But it is right to say the truth plainly: uji alone is not enough for a growing child — it needs protein foods added to it, such as ground groundnuts, milk or eggs.

On names. "Uji" is the Swahili word used in Kenya and Tanzania. Elsewhere in Africa there are foods made in very similar ways: ogi or pap in West Africa, and Ethiopia's injera (though that is a bread). This is an old way of preparing grain found right across the continent, each place with its own name for it.