How to cook
Remove the membranes from the beef livers, sprinkle them with salt and vinegar. Allow to stand for 10-odd minutes, then cut them into pieces and put to fry in preheated oil.
The ready livers are placed in plates. Combine the butter with salt, black pepper, chopped parsley and onions and warm everything on the stove, but do not overcook it.
Finally, season it to taste with lemon juice. Top the beef liver with sauce, salt if needed and serve.