If using bamboo or wooden skewers, place them in water to soak while you prepare the recipe. This can be done several hours ahead and will help keep the skewers from burning up as you grill.
Cut chicken into strips, about one inch wide and three inches long. Place in a large zip top bag.
Mix all the yogurt marinade ingredients together and add to the chicken. Seal the zip top bag and squish everything around until all of the chicken is coated in marinade. Allow to marinate in the refrigerator for at least 1 hour, or up to 24 hours. The longer it sits, the yummier it gets!
Now, for the Tzatziki. Take your Persian cucumber (or 1/2 English cucumber) and peel it. Now grate it up real fine. (Watch your fingers!) Then wrap the grated cucumber in a dish towel and squeeeeeze all the liquid out. You'll end up with about 2tbsp of pretty-dry grated cucumber. Add this to the rest of the ingredients for the Tzatziki in a medium bowl, mix it up, then cover and place in the refrigerator until ready to serve. This can be made ahead and will keep in the fridge for 2-3 days.
Take the chicken out of the refrigerator and let's build the skewers. Thread the chicken strips tightly onto your skewers, almost like you're sewing. You want to thread the chicken just tight enough to keep the meat from drying out as it is grilled, but not so tight that it doesn't completely cook. Once you've threaded one piece on, squish it down a bit and add a slice of red bell pepper (or vegetable of your choice) followed by a few pieces of cut red onion. Repeat with another piece of chicken and the vegetables until you get to the end of the skewer. Finally, cap it all off with a piece of red bell pepper to hold everything on the skewer. Super easy, and looks fancy!
Prepare the grill by wiping the grates with a paper towel dipped in olive oil the heating the grill over medium-high heat. Brush some olive oil over the chicken skewers and sprinkle with salt and pepper. Place the chicken skewers directly over the hottest part of the grill and cook until golden brown and cooked through, turning the skewers to brown all sides, about 10-12 minutes total. Brush with a little more olive oil as they come off the grill.
Serve with your Tzatziki and extra lemon wedges. Maybe a Greek Salad with some Pita or Naan. Enjoy!