For the yogurt dip
Add all the ingredients except the oil in a blender and work the mixture until you get a smooth and very thick paste. Let it stay in the fridge for 30'.
Wet your hands and shape the chickpeas paste into 24 round balls. Heat in a deep pan enough oil and fry the chickpea-balls for 2'-3' or until they get a nice color. Transfer the "revithokeftedes" to a platter lined with paper towels to absorb any excess oil. Serve them accompanied by the sauce.
For the yogurt sauce, put all the ingredients in a bowl and mix well. Leave it in the refrigerator until the moment of serving.