From the message board of CountryLife.net here are two methods for making your own sour cream at home.
Quesco Blanco (queso fresco) is a South American cheese that is similar to the Indian cheese, Panir. It makes a great cooking cheese because it does not melt.
This recipe uses Avocado oil imported from New Zealand. from Elysian Isle Avocado Oils in Oregon.
Recipe uses nettles for a natural thickener or use rennet tablets.