Place cubed chicken, bell peppers and onion chunks into one large bowl and set aside.
In a small bowl, whisk together marinade: lemon juice through chili flakes. Drizzle marinade over the chicken and vegetables. Toss to coat.
Let chicken and vegetables marinade for 20 minutes or room temperature or refrigerated for 30 minutes or up to overnight.
Pre-heat grill to medium-high heat and thread meat and vegetables on to kabobs, alternating between each. (I love these flexible stainless steel kabobs!)
Grill 2-3 minutes per side, rotating four times, or until chicken is cooked through and vegetables are tender.