Wrap onion in cheese cloth and squeeze out as much moisture as possible. Set aside. Place garbanzo beans, parsley, garlic, cumin, coriander, salt, and baking soda in a food processor. Process until the mixture is coarsely pureed. Mix garbanzo bean mixture and onion together in a bowl. Stir in the flour and egg. Shape mixture into 10 small patties and let stand for 15 minutes.
Preheat an oven to 400 degrees F (200 degrees C).
Heat olive oil in a large, oven-safe skillet over medium-high heat. Place the patties in the skillet; cook until golden brown, about 3 minutes on each side.
Transfer skillet to the preheated oven and bake until heated through, about 10 minutes.