Professional tasters warm the glass in one hand, cover it with the other, and then slurp so loudly it sounds like a plumbing problem. The noise is the point — it sprays the oil across your whole palate.

Fruit, bitterness, pepper

Fruit is what you smell: grass, apple, tomato leaf. Bitterness sits on the tongue and means fresh polyphenols. Pepper is the cough at the back of the throat — tasters count coughs as a compliment.

Taste two oils side by side and the differences stop being subtle. That is the entire trick.