Truffle oil has a short shelf life as it degrades quickly. You should, therefore, never buy it because it is bound to be artificially flavoured, even if it has the word "natural" on the bottle: it will simply not be good. As a result, we like to prepare small bottles of the oil ourselves.
Choose some neutral oil, for example grape seed or sunflower oil. 200 grams of Périgord truffle with a good aroma density is sufficient for 1 litre of oil, to which you add a pinch of salt. The oil is ready after 48h in the fridge and the truffle should not be left macerating in the oil any longer than 4 days. The truffle can then be recuperated as a ‘fresh’ truffle for other uses. For the best possible conservation of this oil - which is never longer than a month - the oil should be filtered through a very fine sieve.
It makes an ideal oil for a vinaigrette, and recuperated pieces of truffle are delicious sprinkled over the salad too. The remaining oil can be kept in a hermetically sealed container in the freezer for up to 12 months.