In a small bowl, combine oregano, coriander, cumin, and nutmeg.
In another bowl, whisk together lemon juice, olive oil, and minced garlic.
Pat the chicken dry and season with salt and black pepper.
Coat both sides with the spice mixture.
Add the chicken and diced onion to a large bowl.
Pour the marinade over the chicken and toss until evenly coated.
Marinate for 20–30 minutes at room temperature or refrigerate for 2–4 hours for deeper flavor.
Heat a grill pan or outdoor grill over medium-high heat.
Place lemon halves cut-side down and grill for 2–3 minutes.
Lightly oil the grill.
Grill the Lemon Chicken Recipe for about 6 minutes per side or until the internal temperature reaches 165°F (74°C).
Transfer to a serving platter.
Garnish with grilled lemons and chopped parsley before serving.