Pour the beef stock into a saucepan and reduce it till you're left with 100 grams. Be sure to first weigh the pan, by knowing the weight of the pan it's easy to check the reduced weight.
Pour the reduced beef stock into a bowl and also add the preserved truffle liquid, the balsamic vinegar, the vino santo and grate the preserved truffle in the bowl as well.
Now while stirring add the olive oil and the grape seed oil.
Let all the flavors infuse in your fridge for a couple of hours, I always leave it overnight.
Be sure to give it a little mix before serving it!
