In a large saucepan on the stovetop over high heat, add the split peas and water, cover and bring to a boil. Uncover and skim off any foam. Reduce the heat to medium high and cook for 25-30 minutes until split peas are soft but not mushy. Add the diced potatoes to the boiling water after 15 minutes and cook until soft. The peas and potatoes should be done about the same time. Remove them with a slotted spoon and transfer to a large bowl to cool.
Add the spinach to the boiled water and blanche for 2 minutes. Remove with a slotted spoon and and drain the spinach on several layers of paper towels. Further drain by squeezing the water out of the spinach in the paper towels Chop the drained spinach into bite-size pieces.
When cooled, mash the peas and potatoes together with a potato masher. Add spinach, garbanzo bean flour, diced onion, and all the spices to the mash. Mix all to combine well.
Form ½ - ¾ inch thick patties with a palmful (approx ½ cup) of the mix. You should get about 12 patties.
Heat 1 tablespoon canola oil and 1 tablespoon butter in a non-stick skillet over medium high heat. Fry patties in batches until golden and crispy on both sides. Add more oil and butter with each batch.