I've made some Christmas Cupcakes which only use a small amount of sour cream. What can I do with the rest of the pot?
Fortunately sour cream usually lasts quite well in the fridge and is often used in baking to add moisture. Nigella's Sour Cream Chocolate Cake with Sour Cream Icing from How To Be a Domestic Goddess (p169) or the Guinness Gingerbread from Kitchen (p305) will both help to polish off any leftovers.
Sour cream is also useful as a base for dips and sauces. A very simple mixture of sour cream and chopped dill makes a good accompaniment to plain fish or chicken or you could use it to dress some cooked and cooled baby potatoes for a potato salad. Mixed with chopped chives it makes a classic sauce to dollop on baked potatoes or make the Fully Loaded Potato Skins from Christmas (p40). The Beetroot and Horseradish Sauce in Christmas (p68) can be made with sour cream or creme fraiche and is a lively partner for goose, roast pork or any cold cuts. Nigella also uses sour cream in her Roquamole dip in Nigella Express (p243).
Beef stroganoff is also made with sour cream. Nigella has a recipe in How To Eat (p188) that uses creme fraiche but sour cream can be used instead. The one thing to remember when making pan sauces with sour cream is that the cream will split if it is heated too much so when making the sauce take the pan off the heat before stirring in the sour cream, then warm it gently over a very low heat if needed.