Mayo, aioli, and remoulade

Egg yolk is the emulsifier at the center of all three. Its lecithin holds the oil in fine suspension the same way mustard does in a vinaigrette, but yolk is stronger, which is why mayonnaise can hold far more oil per volume of acid than a dressing can. Oil goes in slowly, especially at the start, because the emulsion is at its most fragile before enough oil has been absorbed to stabilize it.

Room temperature ingredients help. Cold oil poured into cold yolk is more likely to break the emulsion than the same ingredients closer to room temperature, since the fat is stiffer and harder to disperse into fine droplets when it is cold. If a mayonnaise does break, curdling into a thin, greasy mess instead of staying thick, it can usually be rescued by whisking a fresh yolk in a clean bowl and slowly adding the broken mixture back into it.

Mayonnaise is the base recipe on its own: egg yolk, oil, a small amount of acid, usually lemon juice or vinegar, and salt. It is 177 recipes in the catalog, the largest of the three by a wide margin, because it also serves as the starting point for countless flavored versions.

Aioli is mayonnaise built around garlic, either whisked in as a paste before the oil goes in or pounded directly into the emulsion the traditional way, without egg at all in the oldest versions. Most modern aioli recipes do use egg yolk for reliability. The catalog holds 40 aioli recipes, a smaller group than mayonnaise, reflecting how much more assertive and specific the flavor is.

Remoulade starts from a mayonnaise base and adds mustard, capers, pickles, herbs, or hot sauce, depending on the tradition it comes from. It reads as a condiment built for a specific dish, seafood and fried food especially, rather than an all purpose base. The catalog holds 31 remoulade recipes.

The added ingredients in a remoulade are usually chopped fine and folded in after the emulsion is already stable, rather than blended in from the start. Folding, not whisking, keeps those add ins distinct instead of pureeing them into the base, which is part of what gives remoulade its chunkier, more textured character next to a smooth aioli.

Beyond those three names, the catalog carries 111 more recipes filed as a broader egg emulsion category: warm emulsions like hollandaise, and named variations that do not sit cleanly under mayo, aioli, or remoulade. They are built the same way, egg yolk holding fat in suspension, whether that fat is a room temperature oil or warm melted butter.

Hollandaise in particular swaps oil for butter and is built warm over gentle heat rather than cold, which is why it does not travel or hold the same way a cold jarred mayonnaise does. It is best made close to serving.