Add all the dipping sauce ingredients to a small pan with 2 tablespoons of water. Gently bring to the boil, stirring. Boil for around 5 minutes until slightly reduced. Chill.
Parboil potato in boiling water until cooked but not mushy. Mix garbanzo flour with spices, optional cilantro and 1 cup room temperature or warm water. Add onion and potato. Fry around a tablespoon for each pakora, at 375F until dark golden in color. Serve warm with dipping sauce.