In a large bowl, add the chickpeas and baking soda. Cover completely with water. Allow to soak for 18 hours. Drain well, rinse and pat dry.
In a food processor, process chickpeas. Add spices, herbs, garlic and salt and pepper to taste. When the flavor is to your liking, add just enough salt to make it a little more salty. This will work out well when added to the potatoes.
Transfer to a sealed container and refrigerate overnight to allow flavors to meld.
When ready to prepare latkes: in a bowl, combine 1/2 cup falafel paste, onions, potatoes, baking powder, oil and egg. Add a dash of salt and/or pepper if desired. Mix very well.
Heat a 10" skillet over medium heat and add enough oil to completely cover the bottom and rise about 1/4 inch up the sides. Oil is hot enough when a drop of water in the pan sizzles and evaporates almost immediately.
working in batches, spoon heaping tbsps of latke mixture into the pan and flatten slightly until the mound is about 1/4-1/2 inch thick. Fry on one side until golden brown, then flip and repeat on the other side. Once latkes are in the pan, raise heat. adjust temp as necessary to ensure cook is even on both sides and pan is always hot enough.
Transfer latkes to a plate lined with paper towel. Serve hot with tahini or grilled eggplant spread!