The main ingredient of mayonnaise is oil. Mayonnaise is an emulsion made by combining oil with egg yolks, vinegar or lemon juice, and mustard for flavor. The process involves slowly adding the oil to the egg yolk while whisking vigorously or using a blender, allowing the mixture to emulsify and thicken. This rich and creamy condiment is commonly used in various dishes, from salads to sandwiches. It serves as a base for many other sauces, such as aioli and tartar sauce. Home-made mayonnaise is popular for its fresh taste, while store-bought varieties offer convenience and stability.