Mayonnaise began as a French-inspired sauce which is an emulsion of an oil, a vinegar or lemon juice and egg yolk. Egg yolk acts as the emulsifying agent which keeps the oil and vinegar from separating. Sometimes, mustard is used as an emulsifier, too, but more commonly, it is egg yolk.
Other cuisines have adopted mayonnaise and created their own variations by changing up the type of oils and vinegars used in the recipes. In fact, you can experiment with your own homemade mayonnaise concoctions by trying out different oils (soybean, peanut, coconut, etc.) and vinegars (apple cider, rice, white, fruit) as well as adding different herbs and spices. Once you know the basic recipe, your creativity is the only limitation.
But to replicate the traditional Japanese mayonnaise sold in those plastic, squeezable tubes, you can follow the first recipe here. It is creamier in both color and texture than manufactured American mayonnaise which uses distilled white vinegar and fewer egg yolks. If you read the label on the popular Japanese brand Kewpie mayo, it will list “spice” as an ingredient. It is mostly likely a small amount of karashi hot mustard as the Kewpie mayo has a slight tang. Other mayonnaise products will add a pinch of sugar. I like that so I add it in mine.
As for the oil, the Kewpie brand uses a combination of soybean and canola oils while others tend to use generic vegetable oil. You might be tempted to use olive oil for its health benefits, and that is fine but be forewarned that its strong, distinctive flavor note will render a very different taste than that of the Japanese mayonnaise. A milder flavored oil is best. Also, to me, fresh lemon juice provides a brighter flavor than any type of vinegar so I encourage you to try it, too, or maybe a combination of vinegar and lemon juice.
Oh, there is only one important technique in making good mayonnaise and that is to drizzle in the oil slowly to keep the mixture emulsified! You can make homemade mayo by hand, using a whisk, but you must have a strong wrist and the agility to be able to pour in the oil with one hand while whisking quickly with the other. I have neither so I use a blender.
1 cup soybean oil (may substitute vegetable or canola oil)*
2 egg yolks**
1 Tbsp. rice vinegar
2 tsp. fresh lemon juice
˝ tsp. salt
1/8 tsp. karashi hot mustard, optional
pinch of white sugar, optional
1/2 tsp. ajinomoto, optional
Using a blender, immersion blender or small food processor, pour the egg yolks into the mixing bowl. Add the salt, mustard, sugar and ajinomoto (if using). Cover with the lid and blend on medium speed for five seconds. Add the juice and vinegar, and blend again for ten seconds. Then, using the funnel entry of the food processor or the open hole on the blender lid, slowly drizzle in the soybean or vegetable oil while keeping the blender speed on medium-high. The mixture will emulsify and turn thick and creamy in one minute or two. Taste it and adjust for personal preference. You can add more vinegar, lemon juice, sugar or mustard, for example.
Store your homemade mayonnaise in a covered container in the refrigerator. Use it within three days. Do not freeze.
*You can use canola, corn or another light tasting vegetable oil.
**Be sure to wash the shells of your fresh eggs well and pat dry before cracking and separating the yolks. Studies show that the salmonella bacteria that potentially taints raw eggs actually comes from the chicken that lays them and rests on the outer shell, not in the egg white and yolk.