Cheesecloth, a linen napkin or tea towel, or coffee filters
Puree the ricotta, one container at a time, in a blender or food processor. Combine all the ricotta with the milk in a large nonreactive pan. Heat, stirring over low heat, to about 170 degrees. Add the vinegar and continue stirring until the curds begin to separate and the whey begins to drain away.
Line a large stainless steel strainer or colander with the cheesecloth, napkin or towel, or coffee filters.
Place the strainer or colander over a bowl and pour the pureed ricotta into it. Cover the top of the strainer or colander tightly with plastic wrap and refrigerate overnight to allow the ricotta to drain. Before using the ricotta, force the drained cheese through a strainer or colander to lighten it.
© 1990 Nick Malgieri. All rights reserved.