preparing beef or turkey heart for an Oscar

No do not cook it.

But you do have to cut the thing up and remove all the fat, veins and gristle- remove anything not solid red lean meat or it will foul your water. Then you put it through a grinder (meat grinder, vita mix) with whatever amendments you want to add (vitamin powder, garlic, spirulina, whatever) before you bag it and freeze it.
 
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