Kashering Liver

Blood is prohibited, and meat is ordinarily rid of it by salting. Liver is the exception. It holds so much blood that salting cannot draw it out, so liver is kashered by broiling over a fire — the heat drives the blood out directly.

This is one of the few kashrus procedures a household might perform itself, and the details matter.

Before you start: timing

The clock is the part people miss.

• Pour off collected blood immediately. Liver should not sit in blood for twenty-four hours, so empty the bag or container as soon as it arrives.
• Frozen liver must not defrost sitting in its own blood for more than twenty-four hours.
• Thaw completely before broiling begins.
• Kasher within seventy-two hours of defrosting.

Preparing the liver

Beef or calf liver. Remove the fats. Then make deep crisscross cuts, horizontally and vertically — or slice the liver instead. The cuts open channels for the blood to leave. Wash the knife in cold water after cutting raw liver.

Chicken liver. No cutting needed, but make sure the gall bladder has been removed.

Wash the liver after cutting.

Salting and broiling

Salt lightly on both sides — enough salt to give it a good taste, no more. Salt immediately before broiling, because the salt draws out blood and the liver should not then sit in it.

For the broiling itself:

• Use a separate grill or dedicated appliance. A dedicated toaster-type device is one common arrangement.
• Make sure the catch basin collecting the blood is not too close to the liver, so the blood does not come back into contact with it.
• Livers may touch one another and may lie stacked. With beef or calf liver, the cut side should face down.
• If the heat comes only from below, turn the liver — using a utensil designated for this, not a kosher one.
• The liver must be at least two-thirds fully broiled to be considered kashered.

Afterwards

Remove with a fork kept exclusively for this, not a kosher one. Then rinse three times in cold water, after which the liver may be sautéed or cooked normally.

One timing rule applies at the end as well: if three days passed between defrosting and kashering, the liver may be eaten in its broiled state only, and should not be cooked further.

The utensils stay separate

This is the part most often underestimated. Everything used in the process — catch pans, forks, grates, the appliance itself — is treated as non-kosher and kept exclusively for kashering liver.

They may not be washed together with other utensils, and may not be washed in the sink where kosher utensils are washed.

That is a permanent arrangement, not a one-off precaution, and it is worth knowing before you start rather than discovering afterwards.

If any of this is unclear for your situation, ask your rav — and if you are buying liver that has already been kashered, this is what was done to it.