Pour both the milk and the heavy cream into a large stockpot.
Turn the heat on medium and bring the milk to 200 degrees. If you don't have a thermometer, the milk will get a frothy foamy texture on top.
Remove the pot from the burner. Do not let it brown or burn. Turn down the heat if you think this is happening.
Stir in the lemon juice/ vinegar and the salt.
Let the mixture sit for 10 minutes in the stockpot. It should have separated into clumpy white curds and a thin yellowish, watery mixture. If you still see a lot of milky liquid add another tablespoon of lemon juice, stir and wait another five minutes.
Place the strainer over the bowl.
Line the strainer with two pieces of two-ply cheesecloth or a linen dish towel.
Pour or spoon the combined curdled milk and cream into the strainer over the bowl.
Allow the ricotta to drain into the bowl for about 15-60 minutes depending on how wet you would like your ricotta. I find that if I gently turn the mixture every 15-30 minutes it helps the liquid to escape. If you live in a dryer area, you made need less time to drain the excess moisture.
Give the ricotta a taste to adjust the salt.
After this time, scoop the ricotta cheese into an airtight container and refrigerate