Pre-cook liver before frying?

It's not exactly the same for liver, but there is some reason to roast it before frying:

Some people believe in roasting (grilling) before the cooking/frying in order to make the blood drip out of the liver. Can do on fire or in an oven; doesn't matter.

Personally I prefer to go directly to the pan and just fry so it gets less dry. It is definitely sufficient cooking for the liver.

Unlike a heart which would only include residual blood, other organs, especially digestive and some of the defecating body organs, often need extra steps to prepare (eg: kidneys--try cooking them without at least a presoak). Therefore, I would either cook the liver first, or at least marinate it in a vinegar based marinade.