Ingredient

Garlic

Garlic is the rare ingredient whose flavour you create rather than release. A whole clove barely smells of anything. The pungency arrives the moment the cells are broken — and how finely you break them decides how strong the result is, before any heat is involved.

Why the knife decides the flavour

Intact garlic keeps two things apart in separate compartments of the cell: a stable, more or less odourless compound, and an enzyme that acts on it. Cut, crush or chew the clove and the compartments break, the two meet, and the sharp, hot, unmistakable garlic smell is made on the spot.

That is why the cut matters more than the quantity. A whole clove dropped into a stew and fished out gives a mild background. Sliced, it gives sweetness and a gentle bite. Finely chopped, more. Crushed or grated to a paste, most of all, because you have broken the largest possible number of cells. One clove can behave like three depending only on how it met the knife.

The same reaction is why garlic gets stronger for a few minutes after chopping, and why a garlic press produces something noticeably fiercer than the same clove sliced.

Cut it to the strength you want

Whole, peeled, bruised

Mildest. For infusing oil or a braise you will strain. Removable.

Sliced

Sweet and gentle when cooked slowly. The right cut for a slow-cooked tomato sauce or confit.

Chopped

The everyday cut. Enough surface to flavour a pan, coarse enough not to burn instantly.

Crushed or grated

Strongest, and burns fastest of all. Best added late, or off the heat into a dressing.

Raw, in a paste

Fiercest. Aioli, tzatziki and a rubbed salad bowl. A little goes a very long way.

What heat does to it

Cooking destroys the enzyme, so the pungency stops being made and what has already been made starts to break down into gentler, sweeter, more sulphurous compounds. Slow, gentle heat turns garlic sweet and almost nutty. This is why a head of garlic roasted whole for an hour can be spread on bread like butter, and why a raw clove of the same head would take your head off.

Fast, hot cooking does the opposite. Garlic contains sugars and very little water, so it browns quickly and then burns quickly, and burnt garlic is acridly bitter in a way that spreads through everything else in the pan. There is no recovering it — see burnt garlic.

When to add it

The commonest garlic mistake is treating it like onion and putting it in at the same time.

• After the onion, not with it. Onion needs several minutes; garlic needs under one. Give the onion its time first and add the garlic when the onion is nearly where you want it.
• Into fat that is warm, not smoking. Medium heat, thirty to sixty seconds, until it smells like garlic and before it takes any colour beyond pale gold.
• Or at the very end, off the heat, when you want the raw sharpness — stirred into a finished pasta, a dressing or a soup.
• Or at the very beginning in cold oil, brought up slowly together, when you want to infuse the fat and then remove it.

Buying and keeping

• Firm heads with tight, papery skin and no give. Softness means it is drying out inside.
• Green shoots in the centre mean the clove is sprouting. It is not spoiled; the shoot is just more bitter, so pull it out.
• Keep it dry, dark and airy at room temperature — a bowl or a paper bag, not a sealed container and not the fridge, where the cold and the damp push it towards sprouting and mould.
• Pre-chopped garlic in oil or water tastes noticeably duller, because the reaction that makes the flavour happened days ago and the products have been degrading ever since.

How you cut it decides how strong it is

• Garlic has no smell until it is damaged. Cutting ruptures cells and triggers an enzyme reaction that creates the pungent compounds within seconds.
• Whole or lightly crushed — mildest. Perfumes oil or a braise and can be fished out.
• Sliced — moderate. Distinct pieces, sweet when cooked slowly.
• Chopped — stronger.
• Crushed or minced — strongest by a distance, because far more cells are ruptured. A minced clove is several times as assertive as a sliced one.
• Grated to a paste with salt — strongest of all, and the right form for a dressing or a marinade where it stays raw.
• So a recipe calling for "two cloves" is under-specified unless it says how to cut them.

Common questions