The condiment is an emulsion, meaning it combines oil and water (which ordinarily do not mix). To successfully execute an emulsion, the ingredients must be added slowly while quickly mixing nonstop. If that sounds like a lot of work and finicky technique, it's because it is. Texturally, mayo is so persnickety that Costco's creative team actually pulled the plug on developing Kirkland mayo before the product ever hit shelves. Skip the extra steps, advises Garten, and leave laborious mayo-making to the retailers.
In 1913, German immigrant Richard Hellmann opened a Manhattan deli on Columbus Avenue, serving a classic homemade mayo so popular that customers began buying it by the jar. Originally producing two versions, the literal blue ribbon signified the distinction. Within a few years, demand outgrew the counter. Production moved from the deli to a small factory, and the Hellmann's Blue Ribbon Mayonnaise went into clear glass jars that showed exactly what you were buying.