1. Prepare the Liver:
If desired, soak the sliced beef liver in milk for about 30 minutes. This helps to tenderize the liver and reduce its strong flavor. After soaking, drain and pat the liver dry with paper towels.
2. Caramelize the Onions:
In a large skillet or frying pan, melt 2-3 tablespoons of butter or oil over medium heat.
Add the thinly sliced onions to the skillet and sprinkle with a pinch of salt. Cook for about 10-15 minutes, stirring occasionally, until the onions are soft, translucent, and caramelized. If you like, you can add minced garlic during the last 2 minutes of cooking for extra flavor
3. Sear the Liver:
Once the onions are caramelized, push them to the side of the skillet or remove them temporarily to a plate. Increase the heat to medium-high.
Add a bit more butter or oil to the skillet if necessary. Season the beef liver slices with salt and black pepper on both sides.
Carefully place the liver slices in the hot skillet. Sear for about 3-5 minutes on each side, depending on your preferred level of doneness. The liver should be browned on the outside but slightly pink on the inside for optimal tenderness.
4. Combine and Serve:
Once the liver is cooked, return the caramelized onions to the skillet to warm through. If desired, drizzle with a bit of vinegar or lemon juice for added flavor.
Transfer the liver and onions to a serving platter. Garnish with freshly chopped herbs like parsley or thyme, if desired.
5. Enjoy:
Serve the Pan-Seared Beef Liver with Onions immediately, accompanied by your choice of sides, such as mashed potatoes, steamed vegetables, or a fresh salad.