Soak the dried chickpeas in fresh water overnight. (Don't use canned or cooked chickpeas, it won't work as well.)
Drain the soaked chickpeas, and place in a food processor along with the parsey, coriander, onion, and garlic. Process until blended, but not too much—keep a bit of the chunky texture.
Add the cumin, ground coriander, salt, bicarb and flour, and pulse. Alternatively, empty the lot into a large bowl and mix it by hand.
Refrigerate in a covered bowl for at least 15 minutes, up to a couple of hours.
Heat some oil in a frying pan or shallow saucepan, on medium heat.
Shape the falafel mix into balls (with a scant tablespoon per ball), and press into the hot pan to make flattened mini-patties. (I prefer this method to deep-frying, less oil this way.)
Fry until golden-brown, then flip and fry the other side.
Serve immediately, in a fresh pita (or on some quinoa) with hummus, chopped tomato and cucumber, fresh coriander and tahina.