Place the chicken breast in a large bowl and add all the ingredients for the marinade (except the olive oil), then season with salt and pepper. Stir well so that the chicken breast is thoroughly coated with the marinade, and let it marinate (preferably for 1 hour or, even better, overnight).
Heat a generous amount of olive oil in a skillet and fry the chicken thigh fillet until golden brown and cooked through on both sides.
Remove the chicken thigh fillet from the pan, cut into strips, and return it to the pan to fry briefly.
Serve the gyros on flatbread (or pita) with tzatziki, cucumber, and tomato to taste. Enjoy!