The night before, soak the dried chickpeas in cold water enough to cover them by at least 3 inches.
Drain the next day, add to a food processor along with the onion, parsley, garlic, flour, baking powder, salt, cumin, cayenne, and black pepper. Pulse until a chunky paste forms that barely holds together when you press it.
Spread onto a plate, press plastic wrap to the surface, and chill till cold.
Meanwhile heat 2 inches of oil in a heavy-bottomed saucepan.
Shape the falafel dough into small patties using about 2 tablespoons mixture for each ball.
Fry in hot oil 5-6 minutes or until dark golden brown all over. Remove using a slotted spoon.
Serve nestled in pita with your choice of garnishes.