If using wooden skewers, soak them in water for at least 30 minutes to prevent burning.
In a large bowl, combine the olive oil, Ras el Hanout, minced garlic, lemon juice, salt, and pepper.
Add the chicken pieces to the marinade and mix well to coat evenly. Cover and refrigerate for at least 2 hours, or ideally overnight.
When ready to cook, preheat your grill to medium-high heat (around 375-400°F).
Thread the marinated chicken pieces onto skewers, alternating with onion and bell pepper chunks if using.
Oil your grill grates well to prevent sticking.
Place the skewers on the grill and cook for 12-15 minutes, turning every 3-4 minutes until the chicken is cooked through and slightly charred on the edges.
Let rest for 5 minutes before serving.