Emulsifying is a cooking technique used almost every day in the kitchen in which one ingredient is added to another while whisking rapidly. The best example of ingredients that we want to emulsify In making salad dressing are oil and vinegar. They do not naturally dissolve into each other so are called temporary emulsions. When left to sit they separate. Mayonnaise and Hollandaise Sauce, on the other hand, are stable emulsions, which require an emulsifier like eggs, mustard or cream, to hold all other ingredients together. They do not separate. These emulsifiers are used dally in cooking.