Put the 500 g dried chickpeas into a large bowl and cover them generously with cold water. Let them soak for at least 12 hours, but no longer than 24 hours. They will almost double in volume. Under no circumstances use canned chickpeas, otherwise you'll end up with a liquid hummus mixture!
After soaking, drain the chickpeas well and rinse them thoroughly with cold water. It's important that they are well drained before you process them further.
Roughly chop the fresh parsley and fresh cilantro. Peel the garlic cloves.