(These instructions detail cooking the chicken on a stovetop. But the FAQs also have instructions for grilling – whole pieces or small pieces on skewers – as well as baking – on vertical or horizontal skewers)
About 20 minutes before it’s time to cook the chicken get your assembly ingredients and station ready. Remove the chicken and tzatziki from the refrigerator and set them aside. Prep the veggies first, while the chicken warms up a bit for more even cooking. Small dice the cucumber by taking a spoon and carving out the seeded center into the trash. Then, set the cucumber down on a cutting board and slice it into 4-5 long strips. Collect the strips and chop perpendicular to the strips to make small pieces. Set the diced cucuber aside.
Move on to the tomatoes. first, quarter the tomatoes. Then, carve out the seeded center by slicing between the seeds and the curve of the tomato’s flesh with your knife. Slice the remaining tomato into long strips and cut them horizontally in the same manner as the cucumber. When done, set the diced tomatoes aside as well. Lastly, cut the onion in half and then remove the top and the bottom. Place the onion flat-side down on the cuttingboard and cut thin slices from left to right or right to left. (I prefer thin strips, but you can also make thicker strips and chop against them for a dice the same size as the cucumbers and tomatoes. See notes on soaking onions). Set all of the veggies aside.
To cook the chicken, heat a large sauté pan to medium high heat and wait until it is fully heated. Then, add in a bit of oil and let it come back to temperature. Place some of the pieces of chicken into the pan and let them begin to sear. Work in batches. Do not over crowd the pan. The chicken will stick to the pan until a crust builds up enough of a crust for the pieces to release. Once they release, turn the heat down to medium and let the pieces cook until they turn opaque ⅔ -¾ of the way up (unilaterally from bottom to top).
At this point, you can flip the chicken pieces over and let them begin to cook on the other side. They will stick again, be patient and wait for them to release. Depending on the size of your chicken pieces, the second side may be between 3-5 more minutes. Use a thermometer to check that the internal temperature of the chicken has hit 165°F (73.9°C). Once ready, remove the cooked chicken and start the process all over again with the next batch. Repeat until all of the chicken has cooked.
Just before assembly, heat and soften the pita. The simplest way is to lay each piece flat in a pan, on the stovetop, over medium heat. Let the pita cook through for 10-15 seconds on each side before stacking them under a folded kitchen towel to retain heat and moisture.
Now it’s time for assembly. Scoop and spread a good amount of tzatziki onto a pita and then add tomatoes, cucumber, and onion to the flatbread. Finally, top with the chicken and maybe a tad more tzatziki. Roll or fold the pita up and repeat until you have up to 8 chicken gyros.