1 cup heavy cream
1 tablespoon lemon juice or white vinegar
1 tablespoon plain yogurt or buttermilk
Mix the lemon juice or vinegar with the plain yogurt or buttermilk
Stir in the heavy cream
Cover loosely
Let sit at room temperature for 12 to 24 hours until thickened
Stir well
Refrigerate before using
Store in the refrigerator for up to 1 week