Soak the chickpeas for 4 hours at room temperature and up to 24 hours in the fridge.
Drain the chickpeas.
Preheat the oven to 180 C / 360 F.
In a food processor add the onion, garlic, parsley, salt, coriander, cumin and chop.
Add the chickpeas and olive oil and blend until you have a smooth falafel mixture.
Grease the baking sheet with olive oil. We do this do the falafel can crisp up.
Using your hands scoop 2 tablespoons of mixture and shape into patties. Shape the falafel into small patties (they should be about 2 inches wide and ½ inch thick)
Place each falafel on your oiled baking sheet.
Bake for 30 minutes, flipping them gently after 20 minutes.
Tzatziki
Make the tzatziki by grating the cucumber, salt it a tiny bit and squeeze out all the liquid. Mix it with the yogurt, vinegar and garlic.
Assembly
Wash and cut up all the salad ingredients into smaller pieces
Warm the pittas by either placing them in the warm oven for about 2 min or toaster. Oven will make them softer.
Assemble the pittas. Layer each with tzatziki, falafel and salad.