Cut the tomato, onion, and bell pepper (capsicum) into pieces similar in size to the chicken liver so they cook evenly on skewers. I cut them into about 2 inch square pieces, which fit perfectly.
In a mixing bowl, add the chicken liver along with the chopped onion, bell pepper, and tomato. Add all the spices, yogurt, vinegar, and butter. Mix everything well until the chicken and vegetables are evenly coated. Cover and refrigerate for about 30 minutes.
I am making this recipe on charcoal to get an authentic smoky flavor. You can also cook it on a gas stove over low to medium heat. The smoky taste from charcoal is slightly different, but both methods work well.
Now prepare the skewers. Try to place onion pieces at the beginning and end of each skewer. This helps hold everything in place while grilling.
Cook the skewers, turning them from time to time. Brush with butter while cooking to keep them juicy and flavorful.
Finally, your barbecue chicken liver is ready to serve. Before serving, you can add some sliced onions and your favorite sauce or chutney.