The emulsion of oil, egg yolks and lemon juice and seasonings creates this thick creamy dressing. (Without the egg yolks this is called salad dressing.) Commercial mayonnaise is required to be 65% oil.
Refrigerate once opened. Homemade mayonnaise will only last 3-4 days; commercial for up to 6 months.
Used as a spread or as the based for many other sauces.
1/2 cup plain nonfat yogurt + 1/2 cup fat-free mayonnaise = 1 cup low-fat mayonnaise; 1 cup fat-free or reduced-fat sour cream = 1 cup low-fat mayonnaise