Few vegetable groups are as ubiquitous as the allium. This group includes onions, shallots, garlic, scallions and leek, and forms the basis for almost every world cuisine. Alliums are a powerhouse of flavour which when properly harnessed, can completely transform a dish. This month will be all about bite-sized articles focusing on the humble alliums.

We will focus on the two most common members of the family, starting with garlic. Garlic is an interesting ingredient. Depending on how you cook it, it can be incredibly potent or pleasantly mellow. This week, we will address garlic’s more abrasive side. But what makes garlic and other alliums so harsh to begin with?

“The distinctive flavors of the onion family come from its defensive use of the element sulfur. The growing plants take up sulfur from the soil and incorporate it into four different kinds of chemical ammunition, which float in the cell fluids while their enzyme trigger is held separately in a storage vacuole. When the cell is damaged by chopping or chewing, the enzyme escapes and breaks the ammunition molecules in half to produce irritating, strong-smelling sulfurous molecules.”

Harold McGee, On Food and Cooking

This noxious chemical defense is precisely why we cry while chopping onions. Garlic has its own set of chemical ammunition. While a  whole garlic clove has no detectable flavour whatsoever, crushing it releases an enzyme called alliinase, which acts on the sulphur-containing alliin to produce allicin, the compound that gives garlic its harsh pungency. Allicin has become a sort of popcult reference for food nerds thanks to Brad Leone from Bon Apetit, who seems to have a particular obsession with garlic and specially allicin which, he explains is “kind of like a two-part epoxy”, the thing that’s “really really good for you in garlic”.

The more cell walls you damage, the more allicin is produced, more potent is the garlic flavour. This is why a crushed clove of garlic is less potent than sliced garlic, which is less potent than finely chopped garlic. Smush the garlic into a paste, and you’ve got ammunition for a  war against the vampires. Also, smaller cloves tend to be more potent than larger ones. So if you want a mild flavour, use larger cloves. If you want a potent garlic paste, it’s best to stick to the smaller cloves.

The best way to make garlic paste is to finely chop the garlic, add a sprinkling of salt and the smash everything together with the blade of the knife until everything is smooth and homogenous. The salt helps to season the garlic paste and more importantly, its rough crystals act as abrasives that tear apart more cell walls, creating more of that allicin. If you have a lot of garlic to deal with, you could do it in a food processor. One of the most potent garlic applications out there is the middle eastern toum.

Although toum might look like yoghurt with garlic mixed in, there is no dairy or egg in toum. The main ingredient in toum is garlic. Lots and lots of garlic. The flavour compounds of allicin are fat-soluble, which is why using a fat base helps carry its flavour. Think of flavouring olive oil with garlic in an Italian aglio olio, or adding garlic to butter for a good old garlic bread. Toum works on the same principle. At is heart, it is an emulsion made using garlic paste, lemon juice and oil, seasoned with salt. Creamy, smooth with a smack of garlic, toum isn’t for the faint hearted.

Of course, as I have already said, garlic can also be incredibly mild, especially if you cook it. Next time, we will explore the softer side of garlic.