To prevent the bitterness of the liver, wash the beef liver with water and soak it for 1-2 hours in a bowl of milk before you start cooking.
Take the liver pieces in a bowl and pour milk until it covers the liver.
After 2 hours, remove the milk from the bowl and cut the liver into horizontal slices of 3/4 inches thickness.
Take a skillet, add some butter, and heat it on medium flame. When the butter melts, add onions which are cut as rings, into the butter.
When the onions are soft, shift them into a bowl and leave the remaining butter on the skillet.
Now add liver slices into the skillet and put salt and pepper on them. Now, cook the liver pieces for 3-4 minutes on both sides.
After 4 minutes, add the softened onions into the skillet, and fry them along with the liver until the liver turns slightly pink.
Once the liver turns pink, it is good to serve. Frying it longer will make it tough and spoil its taste.
So immediately shift liver pieces and the onions into a serving plate and enjoy the dish.