Set a large sieve over a deep bowl. Dampen 2 layers of cheesecloth with water and line the sieve with the cheesecloth.
Pour the milk and cream into a stainless-steel or enameled pot. Stir in the salt. DO NOT WALK AWAY from the stove top.
Bring to a full boil over medium heat, stirring occasionally. Turn off the heat and stir in the vinegar or lemon juice. Allow the mixture to stand for 1 minute until it curdles. (Add more if you do not see it start to separate.) It will separate into (the curds) and milky parts (the whey).
Carefully pour the mixture into the cheesecloth-lined sieve and allow it to drain into the bowl at room temperature for 20 to 30 minutes, occasionally discarding the liquid that collects in the bowl. The longer you let the mixture drain, the thicker the ricotta. (I like mine thick.) You can even bundle it and give it a gentle squeeze to remove even more moisture.
Transfer the ricotta to a bowl, discarding the cheesecloth and any remaining whey. Use immediately or cover and refrigerate. The ricotta will keep refrigerated for at least 3 days.
