Drain the chickpeas and put them into a food processor.Finely grate in the lemon zest, then add a pinch of sea salt and black pepper, the harissa, allspice, flour and coriander stalks (reserving the leaves for the Coriander & lemon yoghurt, or tasty cooking another day). Blitz until smooth, scraping down the sides of the processor if needed.Scrape out the mixture and use clean, wet hands to quickly divide and shape it into 16 patties.Drizzle 2 tablespoons of olive oil into a large non-stick frying pan on a medium heat. Carefully lay in the falafels and cook for 6 minutes, or until golden and crisp, turning halfway.Warm the pittas in the oven or toast them directly over the flame of a gas hob, using tongs to turn them over.Load the falafels into warm pitta breads with your favourite toppings (see below), then pick over the mint leaves, to serve.