Okara is a by-product from tofu and soy milk production. It is the leftover yellowish pulp after straining all the soy milk is strained out. Okara is very rich in soluble and insoluble fibre, high quality protein, calcium and other minerals. It is mostly used as feed for livestock such as hogs and dairy cows, especially for farms that are in the vicinity of soy milk or tofu factories. The rest of the okara is used as natural nitrogen fertilizer or compost, and a small amount is used in cookery.
The problem or rather advantage with cooking with okara is that it is bland so you cannot really eat it as-is, but then it marries well with whatever flavour you present to it. Since okara is highly perishable, you have to either use it immediately or freeze it for prolonged storage. Replace some or all of ground meat while making burger patties. You can also use okara as an addition to baked goods to give them a crumbly texture.