In a large bowl, whisk together vinegar and salt until salt is dissolved. Whisk in egg, egg yolk, and 2 teaspoons Dijon mustard until well combined. Whisking constantly, slowly drizzle in both oils until emulsified; season with pepper.
Fold in honey, whole-grain mustard, and remaining 2 tablespoons plus 1 1/2 teaspoons Dijon mustard.
Raw eggs should not be used in food prepared for pregnant women, babies, young children, or anyone whose health is compromised.