Add all falafel ingredients to a food processor and pulse several times until a dough is formed. Do not over-process or you will end up with hummus. A little chunky is OK. Transfer ingredients to a separate container or bowl and place in the refrigerator to chill for at least an hour.
To make the tzatziki, first, take the half cucumber and grate it by either using the food processor with grating attachment or by using a hand-held cheese grater. Transfer the grated cucumber to cheesecloth or fine-mesh produce bag and squeeze out the extra moisture.
Using either the food processor or a hand-held mixer, blend the grated cucumber along with all remaining tzatziki ingredients. Transfer to a cup or small container and place in the refrigerator to chill.
Preheat the oven to 375° F. Remove falafel dough from the refrigerator and form 16 - 17 equal-sized balls about 1 1/4" - 1 1/2" in diameter. Place mini-falafels on a parchment-lined baking sheet and place in oven for 30 minutes, flipping sides after 10 and 20 minutes, and once more after 25 minutes, making sure falafels are evenly browned. Once done, let cool for about 10 minutes.
Place all veggie ingredients in a large bowl and toss with tzatziki dressing. Carefully add the mini-falafels to the bowl and gently toss. Eat as is, as lettuce wraps, over salad greens, or inside pita bread, naan, tortillas, or wraps (gluten-free if needed). Enjoy!