Solar Cookers International hears frequently that the concept of soaking beans in water before cooking in order to reduce cooking time seems to be unknown in many parts of the world. In the US, it is common practice to pre-soak dry beans and pulses before cooking.
Method: wash dry beans and cover with water (up to 2 inches, or 10 cm) above the level of the beans. Soak 10-12 hours (overnight), then proceed with usual cooking method.
Ethicurean.com found that pre-soaking rice for half an hour improved efficiency by between 7 and 18 per cent.