In a clean jar or bowl, add the heavy cream and vinegar.
Stir well, then cover loosely with a lid or clean towel.
Let it sit at room temperature for 12–24 hours, or until thickened.
Once it reaches your desired consistency, stir in a pinch of salt if you want, then refrigerate.
It will continue to thicken as it chills. Use within 1–2 weeks.
