Ingredients for preparing a mayonnaise include egg yolks, water, oil, mustard, salt, vinegar, and lemon juice. Use a bowl and whisk, a mixer, or a food processor to prepare a mayonnaise from scratch. For blender mayonnaise use whole eggs. Water is essential to the emulsion and is as important as the yolks in holding the mixture together. Because mayonnaise is made with raw egg yolks, there is always a risk of salmonella poisoning. Use pasteurized eggs to reduce the possibility of food borne illnesses.