To marinate:  In a bowl combine the tomato paste, olive oil, lemon zest, lemon juice, garlic, and spices. Stir to combine. Using a resealable plastic bag or an airtight container combine the marinade and the cubed chicken.  Allow to marinate for at least 2 hours or up to overnight. 

Grilling: If you're in the mood for that irresistible smoky flavor, fire up the grill. Get it to a nice medium-high heat and place skewered, marinated chicken on the grates. Grill for about 6–8 minutes per side, or until your chicken reaches an internal temperature of 165°F. Just don't forget to give wooden skewers a good soak in water for at least 30 minutes before threading on the chicken so that they don't catch fire on the grill.

Baking: Preheat the oven to a toasty 425°F and put the cubed marinated chicken directly on a lightly oiled sheet pan in an even layer. Let it bake for around 15-20 minutes or until the chicken reaches an internal temperature of 165°F. To get crispy bits on the outside of the chicken, once the chicken has cooked through turn the oven to broil and watching closely, allow the edges to caramelize. A few minutes should be enough.