The chickpeas in a large bowl and mash them lightly with a potato masher or fork until you see the skins begin to separate from the peas
This is a bit of a bind, but use your fingers to pick out the skins from the peas and discard
Now grind the coriander and cumin seed using a pestle and mortar or electric grinder and add to the chickpeas with half the olive oil
Peel and crush the garlic and add to the peas with the tahini, lemon juice and some seasoning
Now blend it all together using a hand blender - or you could transfer to the goblet of an electric blender bowl and mix in there, adding more olive oil as necessary (you may need a lot more than you think)
Don't over mix - it is nice if you have a few lumpy bits of chickpea left at the end
Check the taste and if you think it's necessary, add extra seasoning or lemon juice