Dice the onion, fry with butter or vegetable oil. The frying in butter will make the paste softer.
Coarsely grate the carrot, fry alone (without onion).
Rinse the liver, remove the liver membrane if possible, cut it and fry in the frying pan over medium heat. Don’t burn the liver. Sprinkle it with salt and pepper.
Mince all the ingredients in the blender or grinder. You can do it twice to be sure that all the ingredients are properly minced and combined. Stir well.
Add the butter to the paste, you might season it with salt and pepper to taste. Serve cooled, and store the liver paste in the fridge.