- 1/2 pound sliced Black Forest bacon or other lightly salted bacon, cut into 1-inch pieces
- 2 large onions, halved lengthwise and thinly slivered
- 2 pounds calf's liver, sliced 1/2-inch thick
- 1 tablespoon unsalted butter
- Coarse salt and freshly ground black pepper, to taste
- 3 tablespoons sherry vinegar
- 3 tablespoons chicken broth
- 2 tablespoons chopped flat-leaf parsley
- Cook bacon in a large skillet over medium heat until crisp but not burned. Using a slotted spoon, remove bacon to paper towels to drain. Set aside, covered with foil to keep warm.
- In the same skillet, cook the onions over medium heat until wilted and golden, stirring occasionally, about 20 minutes. Remove with a slotted spoon to a bowl, cover and keep warm.
- Cook the liver, 2 slices at a time, for about 1 1/2 minutes per side for medium-rare, adding butter to the skillet if needed. Season with salt and pepper to taste.
- Cut each liver slice on the diagonal into 6 pieces. Arrange on a serving platter and cover loosely with foil.
- Add vinegar and broth to the skillet; bring to a boil, scraping up any brown bits. Add the reserved onions and toss over medium heat for 1 minute to warm through; spoon over the liver and top with bacon. Sprinkle with chopped parsley and serve immediately.