Steps
1. Clean and wash the soybeans and soak them overnight.
2. Boil them in the same water until soft (several hours).
3. Clean and cut up the onions, tomatoes and green peppers.
4. Heat the oil and fry the onions lightly, then add the sweet peppers and tomatoes and fry.
5. Add the salt and the cooked soybeans and allow to simmer until the tomatoes and sweet peppers are cooked.
6. Add the milk, reheat.
7. Season to taste and serve.

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