You need 1 large mixing bowl for the meatball mixture and 1 small bowl. Place the ground chicken into the large bowl. Place the yogurt into the small bowl.
Mince the 3 cloves garlic, 2 go into the large mixing bowl with the chicken and 1 goes into the small bowl with the yogurt.
Chop parsley and add it to the chicken in the large bowl. Slice the scallion greens and add them to the yogurt in the small bowl.
Zest the Lime and add it to the yogurt. Juice half the lime into the yogurt.
For the meatball mixture in the large bowl, add the rest of the ingredients: the ground chicken, garlic, parsley, egg, crumbled feta, oregano, salt, pepper, and breadcrumbs. Mix to fully combine all ingredients.
Then form meatballs by scooping a heaping tablespoon of the mixture and rolling it in your hands. Place them on a sheet pan lined with parchment or aluminum for easy clean-up. Of course, you do not need to line the pan, but if not, then coat the bottom with olive oil. At this point, you can cover them and store in the fridge for up to 3 days before baking. Or place the pan in the freezer to flash-freeze them. Then transfer to a freezer bag or container once frozen.
Using a grater on the medium grate size, grate the cucumber with the skin on. Transfer the cucumber to a clean towel so that you can squeeze the water out of the cucumber before adding it to the yogurt.
If you are not eating the Tzatziki within the next day, then I mix the yogurt sauce without the cucumber and store the cucumber in a separate bowl lined with paper towel to soak up any additional water that comes out of the cucumber. When you are ready, add the cucumber plus salt and pepper to the yogurt, then mix the ingredients into the yogurt. Cover and store in the fridge.