mayonnaise
Also known as: Mayo
A thick, creamy emulsified sauce of oil, egg yolk, and an acid such as vinegar or lemon juice; used as a condiment and as the base for many dressings, dips, and creamy sauces. Being already an emulsion, it's also useful as a coating -- spread thin on food before grilling or roasting, it helps browning and keeps the surface from drying out.
Buying guidance
Standard and 'light' mayonnaise aren't interchangeable in cooking -- light versions have more water and less oil, so they can make a sauce thinner or more prone to separating when heated. Keep it well chilled; as an egg product it softens and separates faster than most condiments if left out.
Substitutions
- Greek yogurt or sour cream -- similar creaminess with more tang and less fat; good in dips and dressings, less good where mayonnaise's job is specifically to hold an emulsion together.
- Vegan or egg-free mayonnaise -- behaves more like real mayonnaise in emulsified sauces than yogurt does.
- Plain oil-based dressing -- not a real substitute for mayonnaise's creaminess or binding, but works if only richness or moisture is needed.
Tips & common mistakes
When it's used as a coating to help browning on something going into the oven or onto a grill, spread it thin -- a thick layer can blacken and turn bitter rather than browning evenly.
Storage
Store-bought mayonnaise is more shelf-stable unopened than its egg content might suggest, thanks to its vinegar or lemon juice; homemade mayonnaise made with raw egg has none of those commercial stabilizers, so treat it like a raw egg product and use it within a few days.