Seeds are the driest and hardest ingredients that cooks deal with. Most require both moisture and heat to make them edible. Most, but not all: the nuts are generally edible and nutritious fresh out of the shell or after a brief application of dry heat, thanks to their relatively tender cell walls and the cells’ content of liquid oil rather than solid starch. But dry grains and legumes are hard and starchy. Hot water softens them by dissolving the strengthening carbohydrates from their cell walls, and moving into the cells to gelate the starch granules and either dissolve or moisten the storage proteins. This makes the seed more nutritious by exposing its nutrients to our digestive enzymes.