Cut the chicken into a large dice, around 1-2 inches
In a large ziplock bag combine the chicken, 4 Tbsp of minced garlic, ½ of a diced red onion, 1 Tbsp oregano, the juice of 1 lemon, 2 Tbsp olive oil, 2 tsp of salt and 1 tsp of pepper. Let it marinate in the refrigerator for at least 20 minutes.
While the chicken is marinating, preheat your oven to 400°F and cut the vegetables into a large dice. Try to make them all the same size.
Spread out the vegetables on a sheet pan and sprinkle with salt and pepper, add 2 Tbsp of minced garlic and 1 Tbsp of balsamic vinegar. Roast for 10-12 minutes.
Prepare the tzatziki sauce by combining all of the ingredients together and mix thoroughly. Store this in a separate container as you don’t want to reheat it in the microwave.
After the chicken is done marinating, heat a grill pan or skillet over medium high heat. If you prefer, the chicken can be put on a skewer but this is not necessary and you can just cook it without the skewer.