Oncom, a By-Product that Proved to be Beneficial for Health - Oncom is a traditional West Java food and closely related to tempe which both are made through fermentation. There are two types of oncom, the red and black ones. The black one is made by using Rhizopusoligosporus, while the red one is Neurosporaintermedia.It is actually a by-product of other food making processes such as the remaining soy pulp, peanut, cassava, or coconut.