Put the milk, cream and salt in a saucepan and bring to a simmer. Stir it occasionally.
When it reaches 195F, turn the heat off and add the lemon juice. Give this two gentle stirs.
Leave it untouched for 6 minutes.
Line a colander with cheesecloth and set it over a bowl. Pour in the mixture.
Let it cool and drain for about 40 minutes.
Cover and put it in the fridge for a few hours or overnight to firm up.
