1 cup heavy cream or whipping cream
1 tablespoon lemon juice or white vinegar
1/4 cup plain yogurt or buttermilk
Mix the cream and lemon juice or vinegar in a clean jar or bowl
Stir in the yogurt or buttermilk
Cover loosely with a lid or clean cloth
Let it sit at room temperature for 12 to 24 hours
Stir once after several hours if desired
Refrigerate until thickened and chilled
Use within 1 to 2 weeks