Place the chickpeas and water in a 5 quart slow cooker .
In a food processor, puree all of the remaining ingredients, except the lemon, onion for garnish and bread.
Add to slow cooker, stir, and cook on High for 10 hours.
Add the half lemon and cook another 2 hours on High. After cooking, remove and discard the lemon.
Top with the sliced red onion and serve with hot naan. (I ran out of naan and wrapped these in warm flour tortillas - very good).
To make half the quantity, use a 3 1/2 qt slow cooker.
Note: I loved these plain, but loved them even more with a cucumber salad. Mix chopped cucumbers - I used seedless - and some chopped red onion if you like, stir in some sour cream or thick yogurt. Spoon onto the chickpeas and naan - the contrast between the spicy chickpeas and the cool creamy cucumbers is out of this world!