Aioli

Halve each clove and flick out any green germ at the center — it is bitter and will sharpen the sauce. Drop the garlic into a heavy mortar with the salt and pound, then grind in circles, working the pestle against the wall of the bowl. The salt is an abrasive; let it shred the garlic for you. Keep going past the point of looking done until you have a completely smooth, sticky, slightly translucent paste with no visible fibers.

If using the optional yolk for insurance, work it smoothly into the garlic paste now. Then begin the oil — and this is the whole game. Add it a single drop, then a thin trickle at a time, grinding the pestle in steady circles always in the same direction. Do not rush. The paste will whiten and thicken with each addition. Only once it is visibly thick and pale and has accepted perhaps a third of the oil may you pour in a slow, pencil-thin stream, still grinding without pause.

Continue streaming in the remaining oil, faster now that the emulsion is strong, until it is all incorporated and the sauce is dense enough to stand up in the mortar in a soft peak. Taste. A few drops of lemon juice will both slacken an overly stiff aioli and brighten the garlic; add salt only if it needs it. Serve at once, mounded in the mortar, alongside grilled meat, rice, or bread — it is at its most fragrant the moment it is made.