Preheat the oven to 425°F (220°C).
In a large mixing bowl, combine chicken, olive oil, honey Dijon mustard, minced garlic, lemon zest, salt, and dry oregano. Mix thoroughly.
Marinate for at least one hour or overnight for enhanced flavor.
If you lack a Vertical Gyro Oven Plate, cut an onion in half, place it on a baking sheet with parchment paper, and stick two wooden skewers vertically in the onion halves to form a DIY spit.
Arrange the marinated chicken thighs on the spit or DIY setup, alternating the direction of each thigh.
Place in the oven and add 1 cup of water or stock to the pan to help create a sauce.
Optionally, cover the top chicken thigh with a small piece of foil to prevent over-browning.
Bake for 75-90 minutes or until the chicken is fully cooked.
Remove from oven, let it rest before slicing, and serve.
