Remove all the membrane surrounding the liver. Remove ducts and arteries.Cut the liver into ¼ inch [0.5 cm] slices. Pat dry the surface with a paper towel.
2. Soaking liver
Place it in a bowl, and soak it previously covering the liver with milk for a minimum of 30 minutes or up to 12 hours. This rest will also make it softer and juicier. Season it with 1 teaspoon salt and pepper.
3. Searing liver
Heat a large skillet over high heat until very hot.Heat a tablespoon of vegetable oil, and sear the liver until well browned, for about 1.5 minutes. If the liver does not detach from the pan, it is not ready to turn yet. Give it a couple of seconds.Turn each piece and brown for an additional minute. At this time, you can check that the internal temperature is between 145 °F and 150 °F [62 °C – 65 °C]. It will finish cooking when you sauté it with the onion. Depending on the size of your pan, you may need to do it in one or two batches.Remove it from the pan, place it on a plate and set aside.
4. Cooking the onions
In the same pan over medium-high heat, place the other tablespoon of oil, melt the butter, and add the onions and bell pepper. Season with the rest of the salt and pepper. Cook and stir the onions until they become translucent and tender.Return the reserved liver to the pan, and sauté it with the onion for a minute.
5. Serving
Taste and add salt and pepper to taste if necessary. Remove it from the heat. Serve immediately.
Video
Notes
The trick to liver that is tender is to cook it the bare minimum. Excess heat will turn it into a rubbery mess.For low-carb eaters, just skip the rice and potato suggestions and serve with low-carb grilled veggies.