It is poured the same of a spoon of soup for each type of oil in 2 glasses. You warm the containing with your hand and move near your nose to the oil, you inhale slowly 2 or 3 times. Memorize and repeat if necessary after 1 minute.
Then, you will taste 2 pieces of bread not salt with a little of oil to take the taste. Or to take 10 drops of oil in the tongue, moving it a for some second. You close the teeth and with the lips a little closed you inhale quickly 2 or 3 times. The oil with the presence of defect must be tasted at last.