Fry the onion and liver. Heat a frying pan, put butter and add onion. Fry until the onion is golden, about 5-7 minutes. Take another frying pan, put it on the fire, melt butter and add pieces of turkey liver, fry for 10 minutes.
Simmer the turkey liver in sour cream sauce. Add the fried onion and sour cream to the pan with the liver. Stir and pour in a glass of water. Cover the pan with a lid and simmer for 25-30 minutes. Then add a little flour and mix thoroughly, add salt and pepper to taste. Simmer for another 5 minutes on low heat.