Cooking fat of your choiceghee, lard or coconut oil preferred
The previous day, rinse the liver slices and put them to marinate overnight in 1/4 cup balsamic vinegar
Rinse the beef liver slices under cold running water and pat them real dry; season liberally with salt and pepper.
Place a heavy bottomed skillet (cast iron preferred) with one or two tablespoons of cooking fat to heat over high heat.
When the pan is really nice and hot, add the liver slices and sear for about 45 seconds to one minute per side, just long enough for them to get a beautiful dark brown and crispy exterior but remain slightly pink on the interior.
Remove the liver slices to a plate and deglaze the pan with 1/4 cup balsamic vinegar. Let the vinegar reduce by about half, which should take approximately 30 seconds. Remove from heat.
Preheat a few tablespoons of cooking fat in a small skillet over medium-high heat. When the pan is hot enough, add the cashews and toss them around until they take a nice golden coloration all around. Sprinkle with salt and set aside.
Divide the arugula, endive, onion slices and avocado between two plates. Slice the liver on a diagonal and place that over the bed salad.
Sprinkle with the warm toasted cashews and balsamic reduction.