Alioli is three ingredients - garlic, salt and oil - and about ten minutes of steady work. That is the entire list, which is why the dish is a good test of technique: with nothing to hide behind, every mistake shows up in the bowl. When it works, it is thick, pale and sharp enough to make steamed vegetables interesting. When it goes wrong, it splits into a greasy puddle and no amount of stirring brings it back.
The version below is the traditional Catalan and Valencian one, made without egg. Mayonnaise is a different dish and a fine one, but this page is about the emulsion that relies on garlic and mechanical force alone. Understanding it also makes the mayonnaise version easier, because the failure points are the same.
The three things that decide the result
First, ratio. One large clove of garlic per 200ml of oil is a starting point; two cloves for people who like it loud. More garlic than that and the emulsion struggles, because garlic carries water and water is the enemy of a stable oil emulsion. Second, temperature: everything should be at room temperature, oil included. Cold oil refuses to blend and will look broken for the first two minutes even when you are doing it right. Third, patience with the salt. Salt is not seasoning here so much as structure - it breaks down the garlic into a paste that can hold the oil.
- Oil: a mild, fresh olive oil for the classic version, or half olive and half neutral if the peppery finish is too much.
- Garlic: young and pale if you can get it; sprouted green cloves turn the whole bowl bitter.
- Salt: coarse, for grinding in the mortar.
- Acid: none in the true recipe. A teaspoon of lemon at the end is common in home kitchens and not wrong.
Method one: mortar and pestle
- Peel two cloves and slice them thin into the mortar with a good pinch of coarse salt.
- Grind to a smooth paste, working the pestle in circles against the wall of the mortar rather than tapping. Two minutes of grinding is normal.
- Add the oil a few drops at a time at first, grinding after each addition as if you were making mayonnaise.
- Once the paste has taken a spoonful of oil and thickened noticeably, you can pour in a thin, steady stream while stirring in one direction.
- Finish with a second small pinch of salt and a taste; the garlic should be assertive but not stinging.
The mortar method produces a denser, slightly coarser alioli that clings to food rather than running. It also takes roughly twice as long, which is why most weeknights in my kitchen start with the second method and end with the mortar only when someone brings good bread.
Method two: blender or food processor
Put the garlic and salt in the jug and blitz to a paste before anything else goes in - this is the step people skip. Scrape down the sides, then start the machine and add the oil in the thinnest stream you can manage, dribbling it down the side of the jug rather than into the blade. The first 50ml are the slow part. After that the mixture will thicken and you can speed up slightly.
Use a jug tall enough that the blade stays covered. A stick blender in a narrow beaker is the best combination of speed and reliability: the ingredients stay under the blade and the whole thing comes together in under two minutes.
Why it breaks, and what to do about it
A split alioli means the oil was added faster than the mixture could absorb it, or the ratio has drifted too far toward oil. The fix is not complicated but it does require a second bowl: start with a teaspoon of the broken mixture in a clean bowl and whisk in the oil as though you were beginning again, then fold the remaining broken sauce into the rescued base in two or three additions. It takes two minutes and always works.
The other common failure is bitterness, which comes from green sprouted garlic or from grinding so hard that the cloves heat up. Stop and taste when the paste is smooth; if it already bites, dilute with a spoon of water before adding more oil rather than trying to fix it at the end.
How thin or thick to take it
Traditional consistency is soft enough to fall off a spoon in a ribbon but firm enough to hold a peak when you drag a spoon through it. If yours is too stiff, beat in a teaspoon of cold water. If it is too loose, it is almost always because the oil went in too fast - rescue it as above rather than adding more garlic.
Where it belongs on the table
- Boiled potatoes and cod, which is the classic pairing in Catalonia and the reason many people first learn the dish.
- Grilled vegetables, especially charred spring onions and leeks straight off the coals.
- Fried potatoes, where a spoonful turns a plate of chips into a reason to stay at the table.
- Roast chicken, spooned over just before serving so the heat releases the garlic.
- Steamed clams or mussels, with the cooking liquor stirred into the bowl first.
- Raw anchovies and bread, for the version of the evening where cooking is out of the question.
Keeping it
Alioli does not keep like a bottled sauce. Made without egg it lasts two days covered in the fridge, and it will darken slightly as the garlic oxidises. Bring it back to room temperature before serving and stir it; it stiffens as it chills. Freezing is not worth the trouble - the emulsion separates on thawing and never fully recovers.
If you want to make a larger batch for a dinner, halve the oil and keep the garlic ratio - a double batch in one bowl is where most people lose the emulsion. Make two batches instead, or invite fewer people. The dish scales badly and that is part of its character: it is meant to be ground for the meal in front of you, set in the middle of the table, and finished before the bread runs out.