Preheat the oven to 350 degrees, then prepare the tzatziki by combining the yogurt, garlic, cucumber*, herbs, lemon juice & salt in a bowl and mixing until well combined. Cover & chill in the refrigerator while you prepare the falafel.
In a large bowl, mash the chickpeas using a fork or a mortar & pestle. Add the onion, garlic, herbs, spices & flour, and mix together to make a thick paste. Roll small amounts if the mixture into ping pong sized balls, then flatten slightly to form small discs.
Line baking sheet with foil. Lightly brush both sides of each falafel disc with the olive oil and place on baking sheet. Bake for about 15 minutes, turning about halfway through the cooking process so they’re evenly browned.
Assemble your sandwiches by stuffing each pita pocket with 2-3 falafel pieces and as many veggies as you can fit in there. Drizzle with a generous amount of tzatziki (or hummus, or tahini, for the purists), and enjoy!