Cut the chicken into chunky cubes size.
Place the olive oil, Greek yogurt or milk, tomato paste, garlic and ginger mince, oregano, all the spices, chili flakes, paprika, freshly ground black pepper, and salt in a bowl and whisk until combined. Add the chicken pieces into the bowl and toss until all the chicken pieces are covered with the marinade.
Cover the bowl, place in the fridge, and let the chicken marinate for a minimum of one hour or preferably overnight.
Cut the bell peppers into chunky cubes similar size to chicken. Thread the chicken and vegetables onto metal or soaked bamboo kebab skewers. If you prefer the peppers can be thread on a separate skewer. I know lot of people like to grill veggies separately.
Cook the kebabs on a BBQ for 12-14 minutes or in the 375°F preheated oven grill for 15 minutes**, until the core temperature reaches (165 °F). Serve with the tomato salad and any other fixings recommended.