Add to a food processor the garlic, bell pepper, tomato, parsley, yogurt, mayo, lemon juice, zest, and jalapeño if using. Blitz until completely puréed.
Cut the chicken into 1-inch cubes, then add the marinade on top.
Add all the spices and massage them into the chicken well. It's best to marinate the chicken for at least 6 hours but it works in just 1 hour as well.
Add chicken cubes onto skewers and grill them on medium-high heat covered for 15-20 minutes, while rotating every few minutes.
Alternatively, soak your wooden skewers for a minimum of 30 minutes in cold water before loading the chicken cubes onto the skewers and placing them on a wire rack. Bake covered at 450℉ for 35-45 minutes or so, while rotating.
Notes
Marinating time: To get the best flavor, marinate the chicken cubes for at least 6 hours. However, if you're pressed for time, even an hour of marinating will infuse the chicken with delicious flavors.Soak wooden skewers: If you're using wooden skewers, soak them in water for at least 30 minutes to prevent them from burning during grilling.Grill temperature: Preheat your grill to medium-high heat to ensure even cooking and a nice char on the chicken.Basting: While grilling, baste the chicken skewers with any leftover marinade for added moisture and flavor.Resting time: Allow the cooked chicken to rest for a few minutes before serving. This helps retain its juices and ensures a tender and juicy bite.