Put slice cut onion and 1 teaspoon of salt into a small bowl and mix them well to reduce the raw onion's bitterness. After you mix them well, wash the onions slices and drain them well.
Add 1 teaspoon of sumac on the drained raw onion slices and mix them well and then set aside. We will use this for serving with liver shish kebab.
Wash the liver and drain well. The liver has a very thin membrane and you need to peel it off. With a small knife, cut through this membrane and peel it off. By doing that, you will also allow the liver to cook faster and smoother.
Cut the liver into cubes 1-inch by1-inch and put in a bowl. Add salt and cumin into this bowl and mix them with liver cubes well.
Put 2 liver cubes and 1 tail fat cube (total 6 liver cubes and 3 tail fat cubes) to the 1 skewer. Continue until all liver cubes and tail fat cubes finish and set aside.
If you are going to use wooden skewers, leave them in water for 10 minutes to prevent them from catching fire. I always recommend stainless steel thin skewers.
Cook Liver Shish on the bbq until all sides of tail fat cubes are golden brown. Once the tail fat turns to golden color, this will also show the liver cooked well. (Don't forget to turn the skewers continuously to keep the liver juice inside the liver.)
Serve with the previously prepared raw onions with sumac.
Tip: Serve with lavash bread and prepared raw onion and sumac mix.
First, Open the lavash bread or tortilla bread. And then put the sumac and raw onion mix into the tortilla bread and then put the liver shish kebab on top. Roll the tortilla bread and voila. You are in food heaven now.