Plasma is the liquid component of blood, in which the red blood cells, white blood cells, and platelets are suspended. It constitutes more than half of the blood's volume and consists mostly of water that contains dissolved salts (electrolytes) and proteins.
Tom is most likely making a Remouillage. It is French for "re-wetting." It is stock that was made from bones that were already used in a previous stock. It is also known as "Second stock." The bones would be re-simmered and fresh mirepoix added. The result of a Remouillage will not be as clear as the original stock and is a bit weaker.
