Cut the chicken liver into small pieces. Wash the liver with clean water 2 to 3 times. Drain well and place the liver in a strainer.
Heat oil in a frying pan over medium heat.
Add the chopped onions, green chilies, and minced garlic to the hot oil. Cook while stirring until the onions turn golden brown.
Add the chopped tomatoes, black pepper powder, cumin powder, salt, turmeric powder, and garam masala. Reduce the heat to low and cook until the tomatoes become soft and well cooked.
Add the chicken liver and mix evenly with the masala. Add half cup of water and cook on medium heat for 8 to 10 minutes.
When the water has completely evaporated and oil separates on the surface, cook for another 1 to 2 minutes. Turn off the flame. The hot chicken liver dish is now ready. Serve with roti, rice, or bread of your choice.