MARINATE CHICKEN: Prepare the chicken breasts by halving each breast horizontally and cover chicken breasts with plastic wrap (to avoid splatter). Using a meat mallet or the bottom of your frying pan, pound breasts to even thickness (you don't want the meat super flat, just even in thickness). Pat dry with a paper towel. Place in a large zipper-top plastic bag. In a bowl, whisk together the honey, oregano, garlic, lemon juice, olive oil, salt and pepper (add to personal preference; I add 1 teaspoon salt and 1/2 teaspoon pepper). Once combined, pour over prepared chicken breasts. Turn to coat and massage into the breasts and then place in the fridge for 20-30 minutes. Marinating too much longer than an hour will cause the chicken to "cook" in the acid.
TZATZIKI: While chicken marinates, prepare the sauce so it can chill before serving. Grate a cucumber with the large holes in a cheese grater. Line a small bowl with a few paper towels (or clean kitchen towel) and place the grated cucumber on top. Squeeze out as much extra moisture as you can from the cucumber (to keep the sauce from being watery). Once it's drained, add to a medium-sized bowl. Add in the Greek yogurt, minced garlic, red wine vinegar, the first lemon half (1/2 teaspoon lemon zest, 1 tablespoon lemon juice), olive oil, and salt and pepper to taste (I add 1/4 teaspoon salt and a pinch of pepper). Refrigerate until ready to serve.
GRILL: Preheat grill to medium heat (400 degrees F). Halve zucchini lengthwise. Shuck corn. Drizzle zucchini halves and corn with olive oil and lightly sprinkle with salt and pepper. Rub the oil and salt/pepper into all sides of the zucchini and corn. Set aside. Remove the chicken from the marinade and discard any remaining marinade. Prepare the fully preheated grill by cleaning and then generously oiling the grill (I drench a rolled-up paper towel in vegetable oil and, holding it with tongs, rub it over the grill grates).
GRILL CONT.: Add the chicken to one side of the grill. Add the zucchini and corn to the other side. Cook the chicken for 4-5 minutes per side or until it registers 160 degrees F (carryover heat will take it to the safe temperature of 165 degrees F). Grill zucchini for 3-5 minutes per side, flipping once. Grill corn about 10 minutes total, flipping every 3-4 minutes until bright yellow and lightly charred. Remove finished ingredients to a plate and cover with foil. Once everything is removed, give the grates a quick clean with the brush. Now add the remaining lemon half to the grill and the pita bread. Grill the lemon for 2-3 minutes (until lightly charred) and the pita bread for 30 seconds to 1 minute per side or until toasted and warmed through.
ZUCCHINI CORN SALAD: Let chicken rest under the foil. Cut the grilled zucchini into half- moons (about 1/2 inch thick) and cut the corn off the cob. Toss in a bowl with the 1 tablespoon shallot. Add a drizzle of olive oil (about 1/2 tablespoon) and then juice the grilled lemon and add to the bowl. Season to taste with salt and pepper (I add about 1/4 teaspoon each). Toss to combine. Tear the pita bread into bite-size pieces.
SERVE: Serve the chicken breasts alongside the zucchini and corn salad, the pita bread and the tzatziki sauce.