Step 1
In a large bowl, stir together the yogurt and garlic; season to taste with salt and pepper. Transfer ½ cup of the yogurt to a medium bowl and reserve for Step 5.
Step 2
Coat the chicken: To the large bowl, add the oregano and stir to combine. Season the chicken all over with 1½ teaspoons salt and a few grinds of pepper. Add the chicken to the large bowl and turn to coat; set aside.
Step 3
Start the salad: Smash the cucumbers with the side of your knife until craggy and split. Rip into ½- to 1-inch pieces and transfer to a colander placed in the sink. Slice or chop the tomatoes into bite-size pieces. Add to the cucumbers along with 1½ teaspoons salt. (It may seem like a lot of salt, but most will drain away.) Toss to combine and leave to drain.
Step 4
In a large nonstick or well-seasoned cast-iron skillet, heat the olive oil over medium. Scrape excess marinade off the chicken, then cook the chicken in batches, adding oil to the pan if necessary, until it’s well browned and releases from the pan, 5 to 7 minutes. Flip and cook until cooked through, another 5 to 7 minutes. Transfer to plates to rest. (For grilling info, see Tip.)
Step 5
To the medium bowl of yogurt, add the feta and mash with a fork until a chunky paste forms. Shake the cucumbers and tomatoes to get rid of any excess moisture. Add to the feta yogurt along with the olives and stir until coated. The balance is dependent on your produce and feta, so season to taste with salt and pepper until flavors are vivid. Eat alongside the chicken.
Tip
To grill the chicken: Heat a grill to medium and clean and grease the grates. Grill the chicken over direct heat until it's well browned and releases from the grates, 5 to 7 minutes. Flip and cook until cooked through, another 5 to 7 minutes. (For a gas grill, close the lid between flips.)
