You prep a kidney by peeling the thin membrane that is on each lobe, then slicing the kidneys in half lengthwise, so you preserve that cool kidney shape. There will be some crunchy hard stuff at the center of the kidneys, which you snip out carefully with kitchen shears or a paring knife. You can eat it, but I don't like the texture. Sear the kidneys in a ripping hot pan and serve them simply. I like them with just good salt and lemon, but a good country mustard is also nice.
1-2tablespoonsgrapeseed or other high smoke-point oil
Juice of a lemon
Coarse finishing salt like fleur de sel
Carefully peel the membranes off the kidneys. Slice them in half lengthwise so you preserve the kidney shape. Cut out the hard, white centers of the kidneys with kitchen shears or a paring knife.
Soak the kidneys in the milk in the refrigerator for 2-3 days. If the milk gets too bloody, change it up to once per day.
Rinse off the kidneys and pat them dry with a paper towel. Sprinkle some kosher salt on them.
Heat a small frying pan on high for 1-2 minutes. Add enough grapeseed oil to put a film on the pan. You don't want the oil too deep or everything will spatter all over the place. Heat this oil for 30 seconds to a minute. You want it hot, but not smoking.
Place the kidneys cut side down in the hot oil so they are not touching. They will want to curl up, so gently press down on them with a spatula. Sear like this for 2 minutes.
Turn the kidneys over and sear in the same way for another 1-2 minutes. Kidneys should still be pink in the middle.
Take the kidneys off the heat and allow to rest on a cutting board for 2-3 minutes. Sprinkle some lemon juice over them. Serve finished with coarse fleur de sel.