In a big bowl, combine yogurt, lemon juice, olive oil, ketchup, garlic, red pepper flakes, salt, cumin, black pepper, paprika, and cinnamon.
Place cubed pork into the yogurt marinade and coat all sides thoroughly. Refrigerate ½ a day or better yet overnight covered with plastic wrap.
Thread the pork, bell peppers and onions tightly and alternately between cubed pork.
If using charcoal, place charcoal in one area and NO charcoal on the opposite side. If using a gas grill, preheat and set to medium heat. Lightly oil the grate before grilling.
Place kabobs where there are no charcoal. Don’t put it directly above the charcoal, it can burn easily due to yogurt marinade. Cover the grill with lid. Check once in a while that there are no flames. Turn kabob when pork unstick from the grill, maybe around 4 minutes or so until all sides are evenly cooked. It is best to use an instant-read thermometer inserted into the center. When internal temperature reaches 145 degrees F, remove from the heat. For more doneness, cover with foil for another 5 minutes. Kabob will continue cooking and temperature will read between 150 to 155 degrees F.
Notes
You can also marinate pork in a zip lock bag.
Put charcoal on one side of grill and cook kabobs on the opposite side without charcoal. It can burn easily due to yogurt.
If not a big fan of pork, use chicken thighs. You can use chicken breast but chicken thighs are much more tender and juicier.
When grilling chicken, thermometer should read at least 165 degrees F (74 degrees C).