Help! Sour cream is nowhere to be found in Africa, and I'm trying to bake a cheesecake. I also noticed that most recipes call for sour cream. Is there any substitute? Can I use buttermilk (homemade as it is also unavailable).
As sour cream has a fat content of around 14% and buttermilk usually has a fat content of under 1% we would not recommend buttermilk as an alternative. Buttermilk also has a more liquid consistency than sour cream which could affect the recipe. You could use creme fraiche but this is generally more difficult to find than sour cream, so we suspect this may not be an alternative available to you.
For a cheesecake a thick natural (plain) yogurt would be the best alternative. The cheesecake may be slightly less rich, depending on the ratio of sour cream to cream cheese in the recipe. If you can get a whole milk Greek style (strained) yogurt then this would be the best one to use. You can also make your own version by straining plain whole milk yogurt. Line a fine-meshed sieve or strainer with a clean piece of muslin or cheesecloth. Spoon yogurt into the lined sieve and set it over a bowl in the fridge and leave it there for 1-2 days, until most of the watery liquid has drained out and the yogurt in the sieve has become slightly thicker.
For cakes it will depend slightly on the recipe, but we would suggest trying with strained yogurt and if the cakes are a little too dry then you could boost the fat content by replacing 1/4 of the yogurt with melted butter (ie use 180ml yogurt plus 60g melted butter for 250ml sour cream = 3/4 cup yogurt plus 1/4 cup melted butter for 1 cup sour cream). Using yogurt instead of sour cream is however more difficult in icings and frostings and we would suggest not using subtitutes in this case, but try another icing instead.