1) Place the drained chickpeas, garlic, salt, and cumin in the work bowl of a food processor.
2) Process until the beans are very finely chopped. With the machine running, drizzle in the oil. If necessary, drizzle in just enough of the reserved chickpea liquid to make the mixture smooth.
3) Remove from the processor, and refrigerate in a covered container until ready to serve. Garnish with a sprig of fresh parsley, if desired.