Created by Mikekey on September 8, 2015
Step 1: In a medium skillet, cook bacon over medium-low heat until crisp, about 10 minutes. Drain; place in bowl.
Step 2: Add onion to bacon fat and cook over low heat until caramelized, stirring often, about 20 minutes.
Step 3: Add onion to bacon; set aside and keep warm.
Step 4: Set a large cast-iron skillet over high heat until hot. Brush liver slices with some of the oil; sprinkle with salt and pepper. Coat the skillet with remaining oil. Quickly saute liver over high heat unitl medium-rare, about 1 minute per side.
Step 5: Arrange liver slices on heated plates. Spoon onion-bacon mixture over the top. Add a few grindings of pepper and pour 1 tsp vinegar over each serving.