Place reserved undressed chickpeas, farro, red onion and parsley into food processor. Add garlic, cumin, salt and flour. Process until mixture starts to round over, forming a ball. Add a little more flour if mixture appears too wet. Take care not to over-mix; a bit of texture is good. If your processor is too small to handle the full quantity of mixture; process in 2 batches with 3 cloves garlic, 1 tablespoon cumin, ¼ teaspoon salt and ¼ cup besan flour in each. Refrigerate mixture for at least 1 hour, then use your hands to roll approximately 48 walnut-sized balls. Pour oil into a deep-sided frying pan, to a height of about 1cm and heat. Test whether the oil is ready by dropping a few breadcrumbs in the pan. They should sizzle as soon as they hit the oil.
Cook falafel in batches, for 3 minutes each side, until dark golden brown. Remove with a slotted spoon and drain on kitchen paper. Spread each pita or lavash bread with tahini sauce, scatter with pickled turnip and follow with tomato and cucumber salad.
Top with 4 or 5 falafel. Roll up and enjoy!