Step 1

In a small bowl, whisk the vinegar into the cornstarch

Step 2

Whisk 2/3 cup of the yogurt into the vinegar mixture

Step 3

Pour the yogurt and vinegar mixture into a small saucepan and cook over high heat, whisking constantly, until it comes to a boil

Step 4

(The yogurt mixture will thicken very quickly

Step 5

) When it is very thick, scrape it into the bowl of a food processor

Step 6

Blend the yogurt mixture for about 1 minute

Step 7

Turn off the food processor and scrape down the sides of the bowl

Step 8

Continue to blend the yogurt mixture until it is slightly cool and very smooth, about 3 more minutes

Step 9

Add the remaining yogurt, mustard, sweetener, and salt to the mixture

Step 10

Blend for another minute

Step 11

Scrape down the sides of the bowl and blend for 30 more seconds

Step 12

Pour the mayonnaise into a plastic container

Step 13

Cover tightly and place in the refrigerator until it is cold and firm, about 2 hours

Step 14

The mayonnaise can be stored in the refrigerator for up to 1 week