Brush the truffles well to remove all particles of grit. Put the fat into a small saucepan; when it is just at boiling point add the truffles. Allow to poach in the scarcely boiling fat for 15 minutes.
Have ready a small sterilized preserving jar. Carefully remove the truffles from the saucepan and place in the jar. Cover with the fat, seal the jar and store in a cool, shady place away