Peel the peppers (they are easier to digest) and cut into strips. Also cut the onions into fine strips. Provide both. Clean, rinse and cut the liver into pieces.
Heat 2 tablespoons of olive oil in a pan and stir-fry the livers for about 4 minutes. Caution: danger of splashing! Take the liver out of the pan. Add the rest of the oil to the pan and sauté the onions and peppers. Pour in the wine and let it boil down. When the peppers are soft, add the livers and season with salt and pepper. Stir in balsamic vinegar and season again.